A Guide to Trade Effluent (TE)

What is Trade Effluent?

Trade Effluent is defined in the Water Industry Act (1991) as:

"any liquid, either with or without particles of matter in suspension in the liquid, which is wholly or partly produced in the course of any trade or industry carried out at a trade premises."

This just means wastewater discharged to the sewer that arises from trade processes occurring on trade premises.

It can occur in many industries such as:

  • Food and drink production
  • Chemical manufacturing
  • Engineering
  • Swimming pools and leisure centres
  • Laundries
  • Vehicle washing
  • Power stations

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

What does this mean to my business?

If you discharge Trade Effluent to the sewer, Section 118 of the Water Industry Act states that you need permission from the Sewerage Undertaker. This usually takes the form of a Trade Effluent Consent. It's an offence to discharge without permission and you could be prosecuted and/or fined for each offence. Even if a Trade Effluent Consent isn't required, prosecution could follow if you discharge something to sewer that damages the sewer, causes blockages, affects the treatment process or that causes environmental pollution. This is in line with the polluter pays principle.

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 make sure that the receiving treatment works can effectively treat the effluent so that it doesn't adversely affect the water recycling process. Trade Effluent regulations are in place to make sure that the environment, public health, sewerage network and treatment works are protected.

How do I know if I need a Consent?

It’s not always clear cut as to whether you'll need a Consent as some Trade Effluent streams may appear to fall under the definition given by the legislation but don’t require a consent. Restaurants and other food-serving establishments fall in to this category although they may need an oil interceptor or fat trap to prevent blockages. 

Temporary wastewater discharges (e.g. building sites) may require a temporary agreement. Mobile businesses such as wheelie-bin cleaning or car valeting will need to make sure the wastewater is discharged at a consented location.

If in any doubt, please get in touch.

How do I get a Trade Effluent Consent?

You'll need to apply for Trade Effluent Consent by completing an application form and sending it to us so we can work with your wholesaler. We'll need some information from you including:

  • Details about your business
  • The process that will generate the effluent
  • The volume and nature of the effluent
  • whether there are any List 1 substances/GMOs contained in the effluent 
  • A site plan showing the desired point of discharge. 

What happens when I complete and return my form?

The wholesaler will take a look at the information you’ve provided and may either issue a consent document containing some conditions or refuse to grant Consent.  

When considering an application, they'll check that any discharge will not impact upon:

  • the sewer system
  • the sewage treatment process
  • the health and safety of any operatives working in or around the sewerage network
  • the environment to which discharge is made.

If Consent is refused or your wholesaler wants to impose a condition, appeals can be made to Ofwat.

How is Trade Effluent checked?

Your Consent may contain conditions for self-monitoring your effluent discharge, in terms of flow or composition. Your wholesaler may decide to routinely sample the effluent to monitor compliance against the Consent and to use in raising treatment charges.

How is Trade Effluent Charged?

Wholesalers use several different mechanisms to charge for Trade Effluent, but it will fall into one or more of the categories below.

  1. It is all charged as domestic sewage (effluent).
  2. It is charged based on fixed strengths via Mogden.
  3. Regular samples are taken to determine the strength of the effluent then charged via Mogden.

What is ‘The Mogden Formula’?

The Mogden Formula is used by Wholesale Water and Sewerage Companies (WaSCs) to calculate the charges due for the treatment of Trade Effluent. It looks complicated but can be thought of as different parts of the effluent treatment process ‘bolted’ together. 

There's some variation between Wholesalers, but in general the formula is as follows:

Charge = R + V + Bv (or M) + B (Ot/Os) + S (St/Ss)

R= Reception and conveyance (for transport of effluent in the sewers)

V= Volumetric (primary treatment charge)

Bv= Volumetric charge for biological treatment (biological treatment charge)

M= Treatment charge (where effluent goes to a sea outfall)

B= Biological treatment charge (biological oxidation charge)

Ot= Measured Chemical Oxygen Demand (Settled)

Os= Regional average Chemical Oxygen Demand (Settled)

S= Sludge (treatment and disposal charge)

St= Measured Suspended Solids (Settled)

Ss= Regional average Suspended Solids (Settled)

Who controls the Mogden charges?

Ofwat publish the standard charges for each Wholesaler on an annual basis.