Trade effluent is liquid waste that is discharged from large or small premises which are used in business, trade or industry.

Examples of trade effluent

Trade effluent may be waste water contaminated with materials such as:

• fats, oils and greases
• chemicals
• detergents
• heavy metal rinses
• solids
• food wastes

Macerated food waste has been banned from sewers in most cases since 1 April 2017.

Examples of common business activities which produce trade effluent include:

• car washes
• laundries
• food and drink production
• chemical manufacturers
• engineering
• swimming pools and leisure centres

What isn't trade effluent?

Liquid wastes which are not classed as trade effluent include:

• domestic sewage, eg wastewater from kitchen sinks, showers and toilets
• clean, uncontaminated surface water, ie clean rainwater which has not been contaminated when running over your site

You will need to comply with legal restrictions regardless of how much trade effluent your business discharges. People working in the confined space of a sewer can be at risk from even very small amounts of some chemicals.

You must get a trade effluent consent or enter into a trade effluent agreement with Northern Ireland Water (NIW) before you discharge trade effluent to a public foul sewer or a private sewer that connects to a public foul sewer.

You will need a trade effluent consent or agreement if you:

• allow any trade effluent to discharge into a public foul sewer
• wash substances such as oils, solvents, chemicals, food, adhesives, inks or powders into a public foul sewer
• use a sink, basin, toilet or gully for disposing of any liquid wastes or discharging wash waters into a public foul sewer, apart from domestic sewage

Domestic sewage includes wastewater from kitchen sinks, domestic washing machines, showers and toilets.

If you discharge trade effluent to a foul sewer without consent you will be committing an offence and may be prosecuted and fined. Discharges made without consent may:

• damage the sewers
• damage sewage treatment works
• cause a health hazard for sewerage workers or the general public
• harm the environment

If you already discharge any quantity of trade effluent to the public foul sewer, no matter how small, without a trade effluent consent or entering into a trade effluent agreement, you should contact NIW immediately.

If you're not sure where your drains connect to public sewers, check whether your site has a drainage plan or speak to NIW for advice.

Consent from the Northern Ireland Environment Agency

You may also need authorisation from the Northern Ireland Environment Agency (NIEA) to discharge some trade effluents to sewer. These include:

• effluents from installations that have a pollution prevention and control permit - you must comply with any requirements on your permit for discharging effluents
• effluents that contain dangerous substances, eg mercury or cadmium

NIEA requirements may be different from the conditions of your trade effluent consent or agreement. You have to comply with the stricter requirements.

Most businesses that discharge to the public foul sewer need a trade effluent consent. Northern Ireland Water (NIW) draws up the consent document on the basis of certain legal rules.

For some discharges you may have a trade effluent agreement - for example, if your trade effluent discharges to the sewage treatment works via a private pipe. NIW has more freedom in the conditions they include in agreements compared with trade effluent consents.

Applying for a trade effluent consent

You will need to apply to NIW if you want to discharge trade effluent into their public foul sewer or to a private sewer that connects to a public foul sewer.

It's always worth ringing NIW as soon as you can, so you can discuss whether your discharge will be acceptable and how long it will take them to process your application.

If your discharge contains certain priority or priority hazardous substances, such as mercury or cadmium, NIW may have to refer your application to the Northern Ireland Environment Agency (NIEA) and the process will take longer.

Appealing against a refused consent

You must not discharge to the public foul sewer until your consent has been granted. If NIW refuses consent you can appeal against that decision. You also have the right to appeal against the conditions in your consent to the Northern Ireland Utility Regulator.

Complying with your trade effluent consent

You must comply with all the conditions of your trade effluent consent. The conditions normally relate to:

• where the discharge may be made
• the rate and maximum volume of the discharge
• the temperature of the discharge
• monitoring and reporting requirements
• how much you need to pay
• the composition of the discharge - including maximum concentrations of specific substances

Changing your trade effluent consent

You must apply for a new or revised trade effluent consent or agreement if:

• the volume or composition of your discharge changes
• you are no longer able to comply with the conditions of your consent or agreement
• you discontinue the discharge and then want to start it again

You should inform NIW immediately if your business changes its registered name or is taken over by another organisation.

If your effluents are unsuitable for discharging to the public foul sewer, or there is no public foul sewer available, you could:

• change your process so you don't produce the effluent
• treat the effluent on site before discharging it to a sewer
• pay for it to be taken away for off-site treatment

If you can't discharge an effluent to the public foul sewer it will be classed as waste. You must comply with your duty of care responsibilities when dealing with your waste.

Effluents you can't discharge to the public foul sewer

Northern Ireland Water (NIW) may not accept discharges of effluents that contain substances which may harm the sewer or treatment process, or be harmful to human health. Harmful substances include:

• oil and fats
• solvents
• working solutions containing heavy metals
• complex organic mixtures
• flammable materials
• other materials likely to damage the sewer, or harm people working in the sewer

NIW will advise you if your effluent can be accepted to the public foul sewer. If it cannot be accepted, you will need to consider other options for treatment or disposal.

What to do if no public foul sewer is available

If there is no public foul sewer immediately available, you may be able to pump your effluent to the nearest public foul sewer - with NIW's permission.

Alternatively, you may treat the effluent on site before discharging it to surface waters or groundwater. You must have a discharge consent, groundwater authorisation or pollution prevention and control (PPC) permit from the Northern Ireland Environment Agency (NIEA) before you discharge treated effluent. If you have a discharge consent, groundwater authorisation or PPC permit, it will specify the maximum concentrations of pollutants allowed in the effluent. You will need to decide how to achieve these limits. You may be able to change your processes, or you could consider using package treatment plants or septic tanks - see using septic tanks, package treatment plants and cesspools.

You must not discharge trade effluent into a surface water sewer, surface waters or groundwater without prior permission.

If you are setting up a new business you should investigate effluent disposal before you choose the location of your business.

If your business is in an area where no mains sewers are available, you may need to treat your effluent on site before discharging it to surface waters or groundwater. You may need to use a wastewater treatment system such as a package treatment plant or septic tank.

Septic tanks and package treatment plants

Septic tanks provide basic sewage treatment. You should make sure the effluent from your septic tank is further treated, for example by a filter or reed bed, before you dispose of it to a watercourse.

You may be able to dispose of the septic tank effluent by soaking it away to ground, for example by using a herringbone drainage field, if you have sufficient land and the drainage conditions are favourable. Permission to do this will depend on the distance of your septic tank from local groundwater sources and other protected areas. You should contact the Northern Ireland Environment Agency (NIEA) for advice.

Correctly operated and well-maintained package treatment plants produce a higher quality effluent which you may be able to discharge to surface water or groundwater.

You will need to carry out a percolation test if you want to use a soakaway or drainage field to dispose of the effluent from your septic tank or package treatment plant. This will confirm whether the area is suitable for a soakaway and will determine the size of the drainage area you need.

If you plan to install a new system or alter your existing system of sewage disposal, you should discuss your plans at an early stage by contacting NIEA.

Authorisation for your septic tank or package treatment plant

You must have a discharge consent, groundwater authorisation or pollution prevention and control permit from NIEA before you discharge any sewage, effluent or contaminated run-off to surface waters or groundwater. NIEA will not normally give you authorisation to discharge if it is reasonable for you to connect to the public sewer.

You may need a waste management license from NIEA if you treat effluent from another business' site.

If you need to construct a new outfall structure for your discharge you will need consent from DfI Rivers.

Cesspools

A cesspool is a watertight tank with no outlet.

You will need to empty your cesspool regularly to prevent it overflowing. Fit an alarm that will go off when your cesspool is nearly full. This is an emergency back-up and you should check the tank regularly.

Maintaining your cesspool or wastewater treatment system

Follow the manufacturer's operating and maintenance instructions to make sure that your wastewater treatment system operates effectively.

You must use a registered waste carrier to empty your cesspool or to remove sludge from your septic tank or treatment plant - you can search NIEA's registered waste carriers database.

You should make sure that clean surface water, for example from roofs and parking areas, does not enter your treatment system. The extra water will reduce the effective capacity of the system and may flush solids out.

You must have permission from Northern Ireland Water (NIW) before you discharge any trade effluent to the public foul sewer. The following measures will help you to minimise the chances of making any discharges accidentally.

Keep a drainage plan of your site

Make sure you have an up-to-date and accurate drainage plan of your site. This will help you identify the locations of all the drains and sewers and where they lead.

You should discharge all trade effluent and sewage to the foul sewer. Only discharge clean, uncontaminated water to the surface water drainage system.

Paint the drainage system manhole covers, gullies and grills on your site in the recognised colour-coding system - blue for surface water drains and red for foul water drains. This will help you identify where any spills will end up.

Manage your materials and practices effectively

Investigate alternative materials and practices that do not produce effluents, eg reuse water for rinsing and cleaning where possible.

Store and handle raw materials, wastes, chemicals and fuels responsibly, so that they cannot enter the surface water and foul water drains on your site.

Keep spill kits near to where you might need them with clear instructions for their use. Make sure your staff know where they are and how to use them.

Spill kits might contain:

• absorbent materials, eg sand
• containment equipment, eg booms
• pumps and suction equipment
• pipe blockers
• drain mats

Make an inventory of all the equipment and materials you have on site. These should be suitable for the type and quantity of fuel, oil and chemicals you store and use.

Ensure you make any visiting contractors aware that they must not discharge any effluents to sewers without checking first that they can.

How to contain spills

You must contain any spills and prevent them from entering site drains. You should also:

• prepare a pollution incident response procedure for dealing with spills and use it in conjunction with your drainage plan - train your staff so that they are aware of the procedure
• report all pollution incidents as soon as they happen to the Northern Ireland Environment Agency (NIEA) on Tel 0800 80 70 60
• inform NIW if you have any spills on your site
• use impermeable upstands around foul water drain entry points to prevent accidental discharge of effluents that are not authorised by NIW - this includes contaminated surface water
• tell your employees and contractors about your procedures for handling, disposing of and discharging liquid wastes - make sure that they comply with them

Reducing and treating your liquid waste can lower your trade effluent bills. You can cut costs by:

• reducing the amount of wastewater you generate overall
• reducing the strength of your trade effluent
• reusing wastewater wherever possible

You can use the Mogden Formula to calculate the cost of discharging trade effluent to sewer.

To reduce costs you could consider:

• checking your meters and meter readings are accurate, especially at sites with more than one trade effluent discharge consent - if the total effluent discharge volume of your site is estimated across a number of discharges, a higher volume may be applied to a higher strength discharge resulting in disproportionate charging
• mixing a higher strength discharge with a lower strength discharge
• evaluating whether an effluent stream from one process can be reused as an input to another process
• treating effluents prior to discharge - eg simple physical or chemical treatment of an effluent stream before discharge to sewer will lower the cost of further treatment by Northern Ireland Water (NIW)
• treating a higher strength effluent to recover for reuse a raw material that would otherwise have been disposed of
• ensuring that the composition or volume of effluents does not breach your consent, as you could be prosecuted and fined
• reducing water use to cut your meter charges and your wastewater bill

Install effluent treatment systems

The cost of discharging trade effluent to a sewer is based on the volume discharged and the concentration of contaminants, so it could be worth installing some form of preliminary treatment system. For example, a simple sedimentation tank could remove a large percentage of the suspended solids in the effluent.

You must comply with your duty of care responsibilities when you dispose of waste from an effluent treatment system. This means you must ensure your waste is handled, recovered and disposed of correctly.

You need to manage and regularly maintain treatment systems to ensure that they are working correctly. Consider whether the benefits of reducing the contaminant load and the cost to discharge outweigh the extra maintenance and operational requirements, as well as the initial capital costs.

Some systems are so effective that you might be able to recover and reuse the effluent on site, saving more water and discharge costs. You may also be able to recover raw materials that could be reused.

Establish effluent discharge procedures

Make sure that your staff record the effluents being discharged accurately, particularly if they are responsible for emptying and discharging effluents from specific processes.

If any new processes are added, this will add to the volume and contaminants being discharged. Check the effluent produced to ensure that your consent is still valid.

Have a site plan that identifies all access and entry points to the sewerage system. Workers responsible for discharging effluents should be made aware that the access and entry points are specifically for trade effluents only. Make sure that any surface water drains can't be mistaken for foul sewer drains.

Trade effluent is liquid waste that is discharged from large or small premises which are used in business, trade or industry.

Examples of trade effluent

Trade effluent may be waste water contaminated with materials such as:

• fats, oils and greases
• chemicals
• detergents
• heavy metal rinses
• solids
• food wastes

Macerated food waste has been banned from sewers in most cases since 1 April 2017.

Examples of common business activities which produce trade effluent include:

• car washes
• laundries
• food and drink production
• chemical manufacturers
• engineering
• swimming pools and leisure centres

What isn't trade effluent?

Liquid wastes which are not classed as trade effluent include:

• domestic sewage, eg wastewater from kitchen sinks, showers and toilets
• clean, uncontaminated surface water, ie clean rainwater which has not been contaminated when running over your site

You will need to comply with legal restrictions regardless of how much trade effluent your business discharges. People working in the confined space of a sewer can be at risk from even very small amounts of some chemicals.

You must get a trade effluent consent or enter into a trade effluent agreement with Northern Ireland Water (NIW) before you discharge trade effluent to a public foul sewer or a private sewer that connects to a public foul sewer.

You will need a trade effluent consent or agreement if you:

• allow any trade effluent to discharge into a public foul sewer
• wash substances such as oils, solvents, chemicals, food, adhesives, inks or powders into a public foul sewer
• use a sink, basin, toilet or gully for disposing of any liquid wastes or discharging wash waters into a public foul sewer, apart from domestic sewage

Domestic sewage includes wastewater from kitchen sinks, domestic washing machines, showers and toilets.

If you discharge trade effluent to a foul sewer without consent you will be committing an offence and may be prosecuted and fined. Discharges made without consent may:

• damage the sewers
• damage sewage treatment works
• cause a health hazard for sewerage workers or the general public
• harm the environment

If you already discharge any quantity of trade effluent to the public foul sewer, no matter how small, without a trade effluent consent or entering into a trade effluent agreement, you should contact NIW immediately.

If you're not sure where your drains connect to public sewers, check whether your site has a drainage plan or speak to NIW for advice.

Consent from the Northern Ireland Environment Agency

You may also need authorisation from the Northern Ireland Environment Agency (NIEA) to discharge some trade effluents to sewer. These include:

• effluents from installations that have a pollution prevention and control permit - you must comply with any requirements on your permit for discharging effluents
• effluents that contain dangerous substances, eg mercury or cadmium

NIEA requirements may be different from the conditions of your trade effluent consent or agreement. You have to comply with the stricter requirements.

Most businesses that discharge to the public foul sewer need a trade effluent consent. Northern Ireland Water (NIW) draws up the consent document on the basis of certain legal rules.

For some discharges you may have a trade effluent agreement - for example, if your trade effluent discharges to the sewage treatment works via a private pipe. NIW has more freedom in the conditions they include in agreements compared with trade effluent consents.

Applying for a trade effluent consent

You will need to apply to NIW if you want to discharge trade effluent into their public foul sewer or to a private sewer that connects to a public foul sewer.

It's always worth ringing NIW as soon as you can, so you can discuss whether your discharge will be acceptable and how long it will take them to process your application.

If your discharge contains certain priority or priority hazardous substances, such as mercury or cadmium, NIW may have to refer your application to the Northern Ireland Environment Agency (NIEA) and the process will take longer.

Appealing against a refused consent

You must not discharge to the public foul sewer until your consent has been granted. If NIW refuses consent you can appeal against that decision. You also have the right to appeal against the conditions in your consent to the Northern Ireland Utility Regulator.

Complying with your trade effluent consent

You must comply with all the conditions of your trade effluent consent. The conditions normally relate to:

• where the discharge may be made
• the rate and maximum volume of the discharge
• the temperature of the discharge
• monitoring and reporting requirements
• how much you need to pay
• the composition of the discharge - including maximum concentrations of specific substances

Changing your trade effluent consent

You must apply for a new or revised trade effluent consent or agreement if:

• the volume or composition of your discharge changes
• you are no longer able to comply with the conditions of your consent or agreement
• you discontinue the discharge and then want to start it again

You should inform NIW immediately if your business changes its registered name or is taken over by another organisation.

If your effluents are unsuitable for discharging to the public foul sewer, or there is no public foul sewer available, you could:

• change your process so you don't produce the effluent
• treat the effluent on site before discharging it to a sewer
• pay for it to be taken away for off-site treatment

If you can't discharge an effluent to the public foul sewer it will be classed as waste. You must comply with your duty of care responsibilities when dealing with your waste.

Effluents you can't discharge to the public foul sewer

Northern Ireland Water (NIW) may not accept discharges of effluents that contain substances which may harm the sewer or treatment process, or be harmful to human health. Harmful substances include:

• oil and fats
• solvents
• working solutions containing heavy metals
• complex organic mixtures
• flammable materials
• other materials likely to damage the sewer, or harm people working in the sewer

NIW will advise you if your effluent can be accepted to the public foul sewer. If it cannot be accepted, you will need to consider other options for treatment or disposal.

What to do if no public foul sewer is available

If there is no public foul sewer immediately available, you may be able to pump your effluent to the nearest public foul sewer - with NIW's permission.

Alternatively, you may treat the effluent on site before discharging it to surface waters or groundwater. You must have a discharge consent, groundwater authorisation or pollution prevention and control (PPC) permit from the Northern Ireland Environment Agency (NIEA) before you discharge treated effluent. If you have a discharge consent, groundwater authorisation or PPC permit, it will specify the maximum concentrations of pollutants allowed in the effluent. You will need to decide how to achieve these limits. You may be able to change your processes, or you could consider using package treatment plants or septic tanks - see using septic tanks, package treatment plants and cesspools.

You must not discharge trade effluent into a surface water sewer, surface waters or groundwater without prior permission.

If you are setting up a new business you should investigate effluent disposal before you choose the location of your business.

If your business is in an area where no mains sewers are available, you may need to treat your effluent on site before discharging it to surface waters or groundwater. You may need to use a wastewater treatment system such as a package treatment plant or septic tank.

Septic tanks and package treatment plants

Septic tanks provide basic sewage treatment. You should make sure the effluent from your septic tank is further treated, for example by a filter or reed bed, before you dispose of it to a watercourse.

You may be able to dispose of the septic tank effluent by soaking it away to ground, for example by using a herringbone drainage field, if you have sufficient land and the drainage conditions are favourable. Permission to do this will depend on the distance of your septic tank from local groundwater sources and other protected areas. You should contact the Northern Ireland Environment Agency (NIEA) for advice.

Correctly operated and well-maintained package treatment plants produce a higher quality effluent which you may be able to discharge to surface water or groundwater.

You will need to carry out a percolation test if you want to use a soakaway or drainage field to dispose of the effluent from your septic tank or package treatment plant. This will confirm whether the area is suitable for a soakaway and will determine the size of the drainage area you need.

If you plan to install a new system or alter your existing system of sewage disposal, you should discuss your plans at an early stage by contacting NIEA.

Authorisation for your septic tank or package treatment plant

You must have a discharge consent, groundwater authorisation or pollution prevention and control permit from NIEA before you discharge any sewage, effluent or contaminated run-off to surface waters or groundwater. NIEA will not normally give you authorisation to discharge if it is reasonable for you to connect to the public sewer.

You may need a waste management license from NIEA if you treat effluent from another business' site.

If you need to construct a new outfall structure for your discharge you will need consent from DfI Rivers.

Cesspools

A cesspool is a watertight tank with no outlet.

You will need to empty your cesspool regularly to prevent it overflowing. Fit an alarm that will go off when your cesspool is nearly full. This is an emergency back-up and you should check the tank regularly.

Maintaining your cesspool or wastewater treatment system

Follow the manufacturer's operating and maintenance instructions to make sure that your wastewater treatment system operates effectively.

You must use a registered waste carrier to empty your cesspool or to remove sludge from your septic tank or treatment plant - you can search NIEA's registered waste carriers database.

You should make sure that clean surface water, for example from roofs and parking areas, does not enter your treatment system. The extra water will reduce the effective capacity of the system and may flush solids out.

You must have permission from Northern Ireland Water (NIW) before you discharge any trade effluent to the public foul sewer. The following measures will help you to minimise the chances of making any discharges accidentally.

Keep a drainage plan of your site

Make sure you have an up-to-date and accurate drainage plan of your site. This will help you identify the locations of all the drains and sewers and where they lead.

You should discharge all trade effluent and sewage to the foul sewer. Only discharge clean, uncontaminated water to the surface water drainage system.

Paint the drainage system manhole covers, gullies and grills on your site in the recognised colour-coding system - blue for surface water drains and red for foul water drains. This will help you identify where any spills will end up.

Manage your materials and practices effectively

Investigate alternative materials and practices that do not produce effluents, eg reuse water for rinsing and cleaning where possible.

Store and handle raw materials, wastes, chemicals and fuels responsibly, so that they cannot enter the surface water and foul water drains on your site.

Keep spill kits near to where you might need them with clear instructions for their use. Make sure your staff know where they are and how to use them.

Spill kits might contain:

• absorbent materials, eg sand
• containment equipment, eg booms
• pumps and suction equipment
• pipe blockers
• drain mats

Make an inventory of all the equipment and materials you have on site. These should be suitable for the type and quantity of fuel, oil and chemicals you store and use.

Ensure you make any visiting contractors aware that they must not discharge any effluents to sewers without checking first that they can.

How to contain spills

You must contain any spills and prevent them from entering site drains. You should also:

• prepare a pollution incident response procedure for dealing with spills and use it in conjunction with your drainage plan - train your staff so that they are aware of the procedure
• report all pollution incidents as soon as they happen to the Northern Ireland Environment Agency (NIEA) on Tel 0800 80 70 60
• inform NIW if you have any spills on your site
• use impermeable upstands around foul water drain entry points to prevent accidental discharge of effluents that are not authorised by NIW - this includes contaminated surface water
• tell your employees and contractors about your procedures for handling, disposing of and discharging liquid wastes - make sure that they comply with them

Reducing and treating your liquid waste can lower your trade effluent bills. You can cut costs by:

• reducing the amount of wastewater you generate overall
• reducing the strength of your trade effluent
• reusing wastewater wherever possible

You can use the Mogden Formula to calculate the cost of discharging trade effluent to sewer.

To reduce costs you could consider:

• checking your meters and meter readings are accurate, especially at sites with more than one trade effluent discharge consent - if the total effluent discharge volume of your site is estimated across a number of discharges, a higher volume may be applied to a higher strength discharge resulting in disproportionate charging
• mixing a higher strength discharge with a lower strength discharge
• evaluating whether an effluent stream from one process can be reused as an input to another process
• treating effluents prior to discharge - eg simple physical or chemical treatment of an effluent stream before discharge to sewer will lower the cost of further treatment by Northern Ireland Water (NIW)
• treating a higher strength effluent to recover for reuse a raw material that would otherwise have been disposed of
• ensuring that the composition or volume of effluents does not breach your consent, as you could be prosecuted and fined
• reducing water use to cut your meter charges and your wastewater bill

Install effluent treatment systems

The cost of discharging trade effluent to a sewer is based on the volume discharged and the concentration of contaminants, so it could be worth installing some form of preliminary treatment system. For example, a simple sedimentation tank could remove a large percentage of the suspended solids in the effluent.

You must comply with your duty of care responsibilities when you dispose of waste from an effluent treatment system. This means you must ensure your waste is handled, recovered and disposed of correctly.

You need to manage and regularly maintain treatment systems to ensure that they are working correctly. Consider whether the benefits of reducing the contaminant load and the cost to discharge outweigh the extra maintenance and operational requirements, as well as the initial capital costs.

Some systems are so effective that you might be able to recover and reuse the effluent on site, saving more water and discharge costs. You may also be able to recover raw materials that could be reused.

Establish effluent discharge procedures

Make sure that your staff record the effluents being discharged accurately, particularly if they are responsible for emptying and discharging effluents from specific processes.

If any new processes are added, this will add to the volume and contaminants being discharged. Check the effluent produced to ensure that your consent is still valid.

Have a site plan that identifies all access and entry points to the sewerage system. Workers responsible for discharging effluents should be made aware that the access and entry points are specifically for trade effluents only. Make sure that any surface water drains can't be mistaken for foul sewer drains.

Trade effluent is liquid waste that is discharged from large or small premises which are used in business, trade or industry.

Examples of trade effluent

Trade effluent may be waste water contaminated with materials such as:

• fats, oils and greases
• chemicals
• detergents
• heavy metal rinses
• solids
• food wastes

Macerated food waste has been banned from sewers in most cases since 1 April 2017.

Examples of common business activities which produce trade effluent include:

• car washes
• laundries
• food and drink production
• chemical manufacturers
• engineering
• swimming pools and leisure centres

What isn't trade effluent?

Liquid wastes which are not classed as trade effluent include:

• domestic sewage, eg wastewater from kitchen sinks, showers and toilets
• clean, uncontaminated surface water, ie clean rainwater which has not been contaminated when running over your site

You will need to comply with legal restrictions regardless of how much trade effluent your business discharges. People working in the confined space of a sewer can be at risk from even very small amounts of some chemicals.

You must get a trade effluent consent or enter into a trade effluent agreement with Northern Ireland Water (NIW) before you discharge trade effluent to a public foul sewer or a private sewer that connects to a public foul sewer.

You will need a trade effluent consent or agreement if you:

• allow any trade effluent to discharge into a public foul sewer
• wash substances such as oils, solvents, chemicals, food, adhesives, inks or powders into a public foul sewer
• use a sink, basin, toilet or gully for disposing of any liquid wastes or discharging wash waters into a public foul sewer, apart from domestic sewage

Domestic sewage includes wastewater from kitchen sinks, domestic washing machines, showers and toilets.

If you discharge trade effluent to a foul sewer without consent you will be committing an offence and may be prosecuted and fined. Discharges made without consent may:

• damage the sewers
• damage sewage treatment works
• cause a health hazard for sewerage workers or the general public
• harm the environment

If you already discharge any quantity of trade effluent to the public foul sewer, no matter how small, without a trade effluent consent or entering into a trade effluent agreement, you should contact NIW immediately.

If you're not sure where your drains connect to public sewers, check whether your site has a drainage plan or speak to NIW for advice.

Consent from the Northern Ireland Environment Agency

You may also need authorisation from the Northern Ireland Environment Agency (NIEA) to discharge some trade effluents to sewer. These include:

• effluents from installations that have a pollution prevention and control permit - you must comply with any requirements on your permit for discharging effluents
• effluents that contain dangerous substances, eg mercury or cadmium

NIEA requirements may be different from the conditions of your trade effluent consent or agreement. You have to comply with the stricter requirements.

Most businesses that discharge to the public foul sewer need a trade effluent consent. Northern Ireland Water (NIW) draws up the consent document on the basis of certain legal rules.

For some discharges you may have a trade effluent agreement - for example, if your trade effluent discharges to the sewage treatment works via a private pipe. NIW has more freedom in the conditions they include in agreements compared with trade effluent consents.

Applying for a trade effluent consent

You will need to apply to NIW if you want to discharge trade effluent into their public foul sewer or to a private sewer that connects to a public foul sewer.

It's always worth ringing NIW as soon as you can, so you can discuss whether your discharge will be acceptable and how long it will take them to process your application.

If your discharge contains certain priority or priority hazardous substances, such as mercury or cadmium, NIW may have to refer your application to the Northern Ireland Environment Agency (NIEA) and the process will take longer.

Appealing against a refused consent

You must not discharge to the public foul sewer until your consent has been granted. If NIW refuses consent you can appeal against that decision. You also have the right to appeal against the conditions in your consent to the Northern Ireland Utility Regulator.

Complying with your trade effluent consent

You must comply with all the conditions of your trade effluent consent. The conditions normally relate to:

• where the discharge may be made
• the rate and maximum volume of the discharge
• the temperature of the discharge
• monitoring and reporting requirements
• how much you need to pay
• the composition of the discharge - including maximum concentrations of specific substances

Changing your trade effluent consent

You must apply for a new or revised trade effluent consent or agreement if:

• the volume or composition of your discharge changes
• you are no longer able to comply with the conditions of your consent or agreement
• you discontinue the discharge and then want to start it again

You should inform NIW immediately if your business changes its registered name or is taken over by another organisation.

If your effluents are unsuitable for discharging to the public foul sewer, or there is no public foul sewer available, you could:

• change your process so you don't produce the effluent
• treat the effluent on site before discharging it to a sewer
• pay for it to be taken away for off-site treatment

If you can't discharge an effluent to the public foul sewer it will be classed as waste. You must comply with your duty of care responsibilities when dealing with your waste.

Effluents you can't discharge to the public foul sewer

Northern Ireland Water (NIW) may not accept discharges of effluents that contain substances which may harm the sewer or treatment process, or be harmful to human health. Harmful substances include:

• oil and fats
• solvents
• working solutions containing heavy metals
• complex organic mixtures
• flammable materials
• other materials likely to damage the sewer, or harm people working in the sewer

NIW will advise you if your effluent can be accepted to the public foul sewer. If it cannot be accepted, you will need to consider other options for treatment or disposal.

What to do if no public foul sewer is available

If there is no public foul sewer immediately available, you may be able to pump your effluent to the nearest public foul sewer - with NIW's permission.

Alternatively, you may treat the effluent on site before discharging it to surface waters or groundwater. You must have a discharge consent, groundwater authorisation or pollution prevention and control (PPC) permit from the Northern Ireland Environment Agency (NIEA) before you discharge treated effluent. If you have a discharge consent, groundwater authorisation or PPC permit, it will specify the maximum concentrations of pollutants allowed in the effluent. You will need to decide how to achieve these limits. You may be able to change your processes, or you could consider using package treatment plants or septic tanks - see using septic tanks, package treatment plants and cesspools.

You must not discharge trade effluent into a surface water sewer, surface waters or groundwater without prior permission.

If you are setting up a new business you should investigate effluent disposal before you choose the location of your business.

If your business is in an area where no mains sewers are available, you may need to treat your effluent on site before discharging it to surface waters or groundwater. You may need to use a wastewater treatment system such as a package treatment plant or septic tank.

Septic tanks and package treatment plants

Septic tanks provide basic sewage treatment. You should make sure the effluent from your septic tank is further treated, for example by a filter or reed bed, before you dispose of it to a watercourse.

You may be able to dispose of the septic tank effluent by soaking it away to ground, for example by using a herringbone drainage field, if you have sufficient land and the drainage conditions are favourable. Permission to do this will depend on the distance of your septic tank from local groundwater sources and other protected areas. You should contact the Northern Ireland Environment Agency (NIEA) for advice.

Correctly operated and well-maintained package treatment plants produce a higher quality effluent which you may be able to discharge to surface water or groundwater.

You will need to carry out a percolation test if you want to use a soakaway or drainage field to dispose of the effluent from your septic tank or package treatment plant. This will confirm whether the area is suitable for a soakaway and will determine the size of the drainage area you need.

If you plan to install a new system or alter your existing system of sewage disposal, you should discuss your plans at an early stage by contacting NIEA.

Authorisation for your septic tank or package treatment plant

You must have a discharge consent, groundwater authorisation or pollution prevention and control permit from NIEA before you discharge any sewage, effluent or contaminated run-off to surface waters or groundwater. NIEA will not normally give you authorisation to discharge if it is reasonable for you to connect to the public sewer.

You may need a waste management license from NIEA if you treat effluent from another business' site.

If you need to construct a new outfall structure for your discharge you will need consent from DfI Rivers.

Cesspools

A cesspool is a watertight tank with no outlet.

You will need to empty your cesspool regularly to prevent it overflowing. Fit an alarm that will go off when your cesspool is nearly full. This is an emergency back-up and you should check the tank regularly.

Maintaining your cesspool or wastewater treatment system

Follow the manufacturer's operating and maintenance instructions to make sure that your wastewater treatment system operates effectively.

You must use a registered waste carrier to empty your cesspool or to remove sludge from your septic tank or treatment plant - you can search NIEA's registered waste carriers database.

You should make sure that clean surface water, for example from roofs and parking areas, does not enter your treatment system. The extra water will reduce the effective capacity of the system and may flush solids out.

You must have permission from Northern Ireland Water (NIW) before you discharge any trade effluent to the public foul sewer. The following measures will help you to minimise the chances of making any discharges accidentally.

Keep a drainage plan of your site

Make sure you have an up-to-date and accurate drainage plan of your site. This will help you identify the locations of all the drains and sewers and where they lead.

You should discharge all trade effluent and sewage to the foul sewer. Only discharge clean, uncontaminated water to the surface water drainage system.

Paint the drainage system manhole covers, gullies and grills on your site in the recognised colour-coding system - blue for surface water drains and red for foul water drains. This will help you identify where any spills will end up.

Manage your materials and practices effectively

Investigate alternative materials and practices that do not produce effluents, eg reuse water for rinsing and cleaning where possible.

Store and handle raw materials, wastes, chemicals and fuels responsibly, so that they cannot enter the surface water and foul water drains on your site.

Keep spill kits near to where you might need them with clear instructions for their use. Make sure your staff know where they are and how to use them.

Spill kits might contain:

• absorbent materials, eg sand
• containment equipment, eg booms
• pumps and suction equipment
• pipe blockers
• drain mats

Make an inventory of all the equipment and materials you have on site. These should be suitable for the type and quantity of fuel, oil and chemicals you store and use.

Ensure you make any visiting contractors aware that they must not discharge any effluents to sewers without checking first that they can.

How to contain spills

You must contain any spills and prevent them from entering site drains. You should also:

• prepare a pollution incident response procedure for dealing with spills and use it in conjunction with your drainage plan - train your staff so that they are aware of the procedure
• report all pollution incidents as soon as they happen to the Northern Ireland Environment Agency (NIEA) on Tel 0800 80 70 60
• inform NIW if you have any spills on your site
• use impermeable upstands around foul water drain entry points to prevent accidental discharge of effluents that are not authorised by NIW - this includes contaminated surface water
• tell your employees and contractors about your procedures for handling, disposing of and discharging liquid wastes - make sure that they comply with them

Reducing and treating your liquid waste can lower your trade effluent bills. You can cut costs by:

• reducing the amount of wastewater you generate overall
• reducing the strength of your trade effluent
• reusing wastewater wherever possible

You can use the Mogden Formula to calculate the cost of discharging trade effluent to sewer.

To reduce costs you could consider:

• checking your meters and meter readings are accurate, especially at sites with more than one trade effluent discharge consent - if the total effluent discharge volume of your site is estimated across a number of discharges, a higher volume may be applied to a higher strength discharge resulting in disproportionate charging
• mixing a higher strength discharge with a lower strength discharge
• evaluating whether an effluent stream from one process can be reused as an input to another process
• treating effluents prior to discharge - eg simple physical or chemical treatment of an effluent stream before discharge to sewer will lower the cost of further treatment by Northern Ireland Water (NIW)
• treating a higher strength effluent to recover for reuse a raw material that would otherwise have been disposed of
• ensuring that the composition or volume of effluents does not breach your consent, as you could be prosecuted and fined
• reducing water use to cut your meter charges and your wastewater bill

Install effluent treatment systems

The cost of discharging trade effluent to a sewer is based on the volume discharged and the concentration of contaminants, so it could be worth installing some form of preliminary treatment system. For example, a simple sedimentation tank could remove a large percentage of the suspended solids in the effluent.

You must comply with your duty of care responsibilities when you dispose of waste from an effluent treatment system. This means you must ensure your waste is handled, recovered and disposed of correctly.

You need to manage and regularly maintain treatment systems to ensure that they are working correctly. Consider whether the benefits of reducing the contaminant load and the cost to discharge outweigh the extra maintenance and operational requirements, as well as the initial capital costs.

Some systems are so effective that you might be able to recover and reuse the effluent on site, saving more water and discharge costs. You may also be able to recover raw materials that could be reused.

Establish effluent discharge procedures

Make sure that your staff record the effluents being discharged accurately, particularly if they are responsible for emptying and discharging effluents from specific processes.

If any new processes are added, this will add to the volume and contaminants being discharged. Check the effluent produced to ensure that your consent is still valid.

Have a site plan that identifies all access and entry points to the sewerage system. Workers responsible for discharging effluents should be made aware that the access and entry points are specifically for trade effluents only. Make sure that any surface water drains can't be mistaken for foul sewer drains.

Trade effluent is liquid waste that is discharged from large or small premises which are used in business, trade or industry.

Examples of trade effluent

Trade effluent may be waste water contaminated with materials such as:

• fats, oils and greases
• chemicals
• detergents
• heavy metal rinses
• solids
• food wastes

Macerated food waste has been banned from sewers in most cases since 1 April 2017.

Examples of common business activities which produce trade effluent include:

• car washes
• laundries
• food and drink production
• chemical manufacturers
• engineering
• swimming pools and leisure centres

What isn't trade effluent?

Liquid wastes which are not classed as trade effluent include:

• domestic sewage, eg wastewater from kitchen sinks, showers and toilets
• clean, uncontaminated surface water, ie clean rainwater which has not been contaminated when running over your site

You will need to comply with legal restrictions regardless of how much trade effluent your business discharges. People working in the confined space of a sewer can be at risk from even very small amounts of some chemicals.

You must get a trade effluent consent or enter into a trade effluent agreement with Northern Ireland Water (NIW) before you discharge trade effluent to a public foul sewer or a private sewer that connects to a public foul sewer.

You will need a trade effluent consent or agreement if you:

• allow any trade effluent to discharge into a public foul sewer
• wash substances such as oils, solvents, chemicals, food, adhesives, inks or powders into a public foul sewer
• use a sink, basin, toilet or gully for disposing of any liquid wastes or discharging wash waters into a public foul sewer, apart from domestic sewage

Domestic sewage includes wastewater from kitchen sinks, domestic washing machines, showers and toilets.

If you discharge trade effluent to a foul sewer without consent you will be committing an offence and may be prosecuted and fined. Discharges made without consent may:

• damage the sewers
• damage sewage treatment works
• cause a health hazard for sewerage workers or the general public
• harm the environment

If you already discharge any quantity of trade effluent to the public foul sewer, no matter how small, without a trade effluent consent or entering into a trade effluent agreement, you should contact NIW immediately.

If you're not sure where your drains connect to public sewers, check whether your site has a drainage plan or speak to NIW for advice.

Consent from the Northern Ireland Environment Agency

You may also need authorisation from the Northern Ireland Environment Agency (NIEA) to discharge some trade effluents to sewer. These include:

• effluents from installations that have a pollution prevention and control permit - you must comply with any requirements on your permit for discharging effluents
• effluents that contain dangerous substances, eg mercury or cadmium

NIEA requirements may be different from the conditions of your trade effluent consent or agreement. You have to comply with the stricter requirements.

Most businesses that discharge to the public foul sewer need a trade effluent consent. Northern Ireland Water (NIW) draws up the consent document on the basis of certain legal rules.

For some discharges you may have a trade effluent agreement - for example, if your trade effluent discharges to the sewage treatment works via a private pipe. NIW has more freedom in the conditions they include in agreements compared with trade effluent consents.

Applying for a trade effluent consent

You will need to apply to NIW if you want to discharge trade effluent into their public foul sewer or to a private sewer that connects to a public foul sewer.

It's always worth ringing NIW as soon as you can, so you can discuss whether your discharge will be acceptable and how long it will take them to process your application.

If your discharge contains certain priority or priority hazardous substances, such as mercury or cadmium, NIW may have to refer your application to the Northern Ireland Environment Agency (NIEA) and the process will take longer.

Appealing against a refused consent

You must not discharge to the public foul sewer until your consent has been granted. If NIW refuses consent you can appeal against that decision. You also have the right to appeal against the conditions in your consent to the Northern Ireland Utility Regulator.

Complying with your trade effluent consent

You must comply with all the conditions of your trade effluent consent. The conditions normally relate to:

• where the discharge may be made
• the rate and maximum volume of the discharge
• the temperature of the discharge
• monitoring and reporting requirements
• how much you need to pay
• the composition of the discharge - including maximum concentrations of specific substances

Changing your trade effluent consent

You must apply for a new or revised trade effluent consent or agreement if:

• the volume or composition of your discharge changes
• you are no longer able to comply with the conditions of your consent or agreement
• you discontinue the discharge and then want to start it again

You should inform NIW immediately if your business changes its registered name or is taken over by another organisation.

If your effluents are unsuitable for discharging to the public foul sewer, or there is no public foul sewer available, you could:

• change your process so you don't produce the effluent
• treat the effluent on site before discharging it to a sewer
• pay for it to be taken away for off-site treatment

If you can't discharge an effluent to the public foul sewer it will be classed as waste. You must comply with your duty of care responsibilities when dealing with your waste.

Effluents you can't discharge to the public foul sewer

Northern Ireland Water (NIW) may not accept discharges of effluents that contain substances which may harm the sewer or treatment process, or be harmful to human health. Harmful substances include:

• oil and fats
• solvents
• working solutions containing heavy metals
• complex organic mixtures
• flammable materials
• other materials likely to damage the sewer, or harm people working in the sewer

NIW will advise you if your effluent can be accepted to the public foul sewer. If it cannot be accepted, you will need to consider other options for treatment or disposal.

What to do if no public foul sewer is available

If there is no public foul sewer immediately available, you may be able to pump your effluent to the nearest public foul sewer - with NIW's permission.

Alternatively, you may treat the effluent on site before discharging it to surface waters or groundwater. You must have a discharge consent, groundwater authorisation or pollution prevention and control (PPC) permit from the Northern Ireland Environment Agency (NIEA) before you discharge treated effluent. If you have a discharge consent, groundwater authorisation or PPC permit, it will specify the maximum concentrations of pollutants allowed in the effluent. You will need to decide how to achieve these limits. You may be able to change your processes, or you could consider using package treatment plants or septic tanks - see using septic tanks, package treatment plants and cesspools.

You must not discharge trade effluent into a surface water sewer, surface waters or groundwater without prior permission.

If you are setting up a new business you should investigate effluent disposal before you choose the location of your business.

If your business is in an area where no mains sewers are available, you may need to treat your effluent on site before discharging it to surface waters or groundwater. You may need to use a wastewater treatment system such as a package treatment plant or septic tank.

Septic tanks and package treatment plants

Septic tanks provide basic sewage treatment. You should make sure the effluent from your septic tank is further treated, for example by a filter or reed bed, before you dispose of it to a watercourse.

You may be able to dispose of the septic tank effluent by soaking it away to ground, for example by using a herringbone drainage field, if you have sufficient land and the drainage conditions are favourable. Permission to do this will depend on the distance of your septic tank from local groundwater sources and other protected areas. You should contact the Northern Ireland Environment Agency (NIEA) for advice.

Correctly operated and well-maintained package treatment plants produce a higher quality effluent which you may be able to discharge to surface water or groundwater.

You will need to carry out a percolation test if you want to use a soakaway or drainage field to dispose of the effluent from your septic tank or package treatment plant. This will confirm whether the area is suitable for a soakaway and will determine the size of the drainage area you need.

If you plan to install a new system or alter your existing system of sewage disposal, you should discuss your plans at an early stage by contacting NIEA.

Authorisation for your septic tank or package treatment plant

You must have a discharge consent, groundwater authorisation or pollution prevention and control permit from NIEA before you discharge any sewage, effluent or contaminated run-off to surface waters or groundwater. NIEA will not normally give you authorisation to discharge if it is reasonable for you to connect to the public sewer.

You may need a waste management license from NIEA if you treat effluent from another business' site.

If you need to construct a new outfall structure for your discharge you will need consent from DfI Rivers.

Cesspools

A cesspool is a watertight tank with no outlet.

You will need to empty your cesspool regularly to prevent it overflowing. Fit an alarm that will go off when your cesspool is nearly full. This is an emergency back-up and you should check the tank regularly.

Maintaining your cesspool or wastewater treatment system

Follow the manufacturer's operating and maintenance instructions to make sure that your wastewater treatment system operates effectively.

You must use a registered waste carrier to empty your cesspool or to remove sludge from your septic tank or treatment plant - you can search NIEA's registered waste carriers database.

You should make sure that clean surface water, for example from roofs and parking areas, does not enter your treatment system. The extra water will reduce the effective capacity of the system and may flush solids out.

You must have permission from Northern Ireland Water (NIW) before you discharge any trade effluent to the public foul sewer. The following measures will help you to minimise the chances of making any discharges accidentally.

Keep a drainage plan of your site

Make sure you have an up-to-date and accurate drainage plan of your site. This will help you identify the locations of all the drains and sewers and where they lead.

You should discharge all trade effluent and sewage to the foul sewer. Only discharge clean, uncontaminated water to the surface water drainage system.

Paint the drainage system manhole covers, gullies and grills on your site in the recognised colour-coding system - blue for surface water drains and red for foul water drains. This will help you identify where any spills will end up.

Manage your materials and practices effectively

Investigate alternative materials and practices that do not produce effluents, eg reuse water for rinsing and cleaning where possible.

Store and handle raw materials, wastes, chemicals and fuels responsibly, so that they cannot enter the surface water and foul water drains on your site.

Keep spill kits near to where you might need them with clear instructions for their use. Make sure your staff know where they are and how to use them.

Spill kits might contain:

• absorbent materials, eg sand
• containment equipment, eg booms
• pumps and suction equipment
• pipe blockers
• drain mats

Make an inventory of all the equipment and materials you have on site. These should be suitable for the type and quantity of fuel, oil and chemicals you store and use.

Ensure you make any visiting contractors aware that they must not discharge any effluents to sewers without checking first that they can.

How to contain spills

You must contain any spills and prevent them from entering site drains. You should also:

• prepare a pollution incident response procedure for dealing with spills and use it in conjunction with your drainage plan - train your staff so that they are aware of the procedure
• report all pollution incidents as soon as they happen to the Northern Ireland Environment Agency (NIEA) on Tel 0800 80 70 60
• inform NIW if you have any spills on your site
• use impermeable upstands around foul water drain entry points to prevent accidental discharge of effluents that are not authorised by NIW - this includes contaminated surface water
• tell your employees and contractors about your procedures for handling, disposing of and discharging liquid wastes - make sure that they comply with them

Reducing and treating your liquid waste can lower your trade effluent bills. You can cut costs by:

• reducing the amount of wastewater you generate overall
• reducing the strength of your trade effluent
• reusing wastewater wherever possible

You can use the Mogden Formula to calculate the cost of discharging trade effluent to sewer.

To reduce costs you could consider:

• checking your meters and meter readings are accurate, especially at sites with more than one trade effluent discharge consent - if the total effluent discharge volume of your site is estimated across a number of discharges, a higher volume may be applied to a higher strength discharge resulting in disproportionate charging
• mixing a higher strength discharge with a lower strength discharge
• evaluating whether an effluent stream from one process can be reused as an input to another process
• treating effluents prior to discharge - eg simple physical or chemical treatment of an effluent stream before discharge to sewer will lower the cost of further treatment by Northern Ireland Water (NIW)
• treating a higher strength effluent to recover for reuse a raw material that would otherwise have been disposed of
• ensuring that the composition or volume of effluents does not breach your consent, as you could be prosecuted and fined
• reducing water use to cut your meter charges and your wastewater bill

Install effluent treatment systems

The cost of discharging trade effluent to a sewer is based on the volume discharged and the concentration of contaminants, so it could be worth installing some form of preliminary treatment system. For example, a simple sedimentation tank could remove a large percentage of the suspended solids in the effluent.

You must comply with your duty of care responsibilities when you dispose of waste from an effluent treatment system. This means you must ensure your waste is handled, recovered and disposed of correctly.

You need to manage and regularly maintain treatment systems to ensure that they are working correctly. Consider whether the benefits of reducing the contaminant load and the cost to discharge outweigh the extra maintenance and operational requirements, as well as the initial capital costs.

Some systems are so effective that you might be able to recover and reuse the effluent on site, saving more water and discharge costs. You may also be able to recover raw materials that could be reused.

Establish effluent discharge procedures

Make sure that your staff record the effluents being discharged accurately, particularly if they are responsible for emptying and discharging effluents from specific processes.

If any new processes are added, this will add to the volume and contaminants being discharged. Check the effluent produced to ensure that your consent is still valid.

Have a site plan that identifies all access and entry points to the sewerage system. Workers responsible for discharging effluents should be made aware that the access and entry points are specifically for trade effluents only. Make sure that any surface water drains can't be mistaken for foul sewer drains.