Discharging trade effluent

How to avoid unauthorised effluent discharges


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