Trade effluent consent

If you plan to discharge trade effluent to the public sewer you’re required by law to obtain a trade effluent consent

What is trade effluent?

Trade effluent is defined as any wastewater, other than domestic or surface water which is discharged from a process or activity that is carried out by a commercial or industrial customer.

Trade effluent can arise from many industries, such as:

  • food and drink production
  • chemical manufacturing
  • engineering
  • swimming pools and leisure centres
  • laundries
  • vehicle washing
  • photographic processing
  • power stations

Trade Effluent can also arise from day to day essential services such as hospitals and local authorities.

Why is trade effluent controlled?

All wastewater entering the public sewer is carried to the local water recycling works to be treated, cleaned and safely returned to the environment. Controls need to be in place to ensure that the receiving treatment works can effectively treat the effluent to ensure that it does not adversely affect the water recycling process. Trade Effluent is heavily regulated to ensure that the environment, public health and treatment works are protected.

What is a trade effluent consent?

A consent is a legal document issued by the relevant sewage undertaker, responsible for the upkeep of the public sewer, under the powers provided within the Water Industry Act 1991. A consent contains a number of conditions and limitations around the quality and quantity of the discharge.

Do I require a trade effluent consent?
You will need to have permission, by law, to legally discharge any Trade Effluent into the public sewer. You can obtain permission with a Trade Effluent consent. Discharging effluent without a consent is an offence and you may be subject to legal action if you do so.

What happens if I breach my consented limits?
Failure to comply with the consented conditions is an offence under Section 121 of the Water Industry Act 1991 (England) and the Sewerage Act 1968 (Scotland). Enforcement action can be taken against companies who fail to comply, which may result in prosecution.

How are trade effluent charges calculated?

Charges are calculated for the disposal and treatment of trade effluent. Charges are related to the volume discharged and the strength of Chemical Oxygen Demand (COD) and Suspended Solids (SS).

A charging mechanism called the Mogden Formula is used to calculate charges, and is applied as follows:

C = R + VB + (Ot/Os x B) + (St/Ss x S)

C = total cost of conveying and treating the trade effluent discharge (in pence per cubic metre)
R = cost of conveyance through the sewage system and reception at the water recycling centres (in pence per cubic metre)
VB = cost of volumetric and primary treatment (screening and settlement) at the water recycling centres (in pence per cubic metre)
Ot = the mean strength of the trade effluent measured by chemical oxygen demand (settled) (in milligrams per litre)
Os = the mean strength of the settled sewage at water recycling centres measured by chemical oxygen demand (total) (in milligrams per litre)
B = cost of biological treatment at the water recycling centres (in pence per cubic metre)
St = the mean suspended solids content of the trade effluent (in milligrams per litre)
Ss = the mean suspended solids content of crude sewage at water recycling centres (in milligrams per litre)
S = cost of the treatment and recycling/disposal of biosolids (solid material) (in pence per cubic metre)

Customers in England who are in the Anglian Water region fall into two main categories of charging; Fixed Strengths and Regional Strengths. Only the Fixed Strength charging category is used in Scotland.

  • Fixed Strengths are the average COD and SS values recorded in a trader’s discharge and are applied until the figures are due for review.
  • In Scotland, Fixed Strengths are reviewed annually, however for customers within the Anglian Water region in England, the review period is based on the volume of discharge.
  • Regional Strengths (Customers within the Anglian Water region only) are a fixed value of COD and SS for certain types of trade, such as car washes and swimming pools, where the strength of effluent varies very little between traders operating within the same industry.

Customers supplied within the Anglian Water region in England incur an annual fixed charge for Trade Effluent. The value of this charge is dependent on the chosen tariff. Further details can found under our Tariffs section.

Customers in Scotland incur an availability charge. This charge is calculated using an alternative version of the Mogden Formula.

C = No. of days x [CDV x (Ra +Va)] + (Ba x sBODl) + (Sa x TSSl)

A joint venture between Anglian Water Business and NWG business