Discharging trade effluent

Do I need consent to discharge trade effluent?


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 (NIEA)

You may also need authorisation from the 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.