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 covers the majority of wastewaters produced by trade processes.

If you’d like to take a look at the Act it can be found here: www.legislation.gov.uk/ukpga/1991/56

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 is an offence to discharge without permission and you could be prosecuted and/or fined for each offence.  Even if a Trade Effluent Consent is not 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 Principal.

How do I know if I need a Consent?

It’s not always clear cut as to whether you will 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/fat trap to prevent blockages. 

Temporary discharges (e.g. building sites) may or may not require a temporary agreement.  Mobile businesses such as Wheelie-bin cleaning or car valeting will need to ensure the effluent produced is recovered and discharged at a Consented location.

If in any doubt, your wholesaler will be able to help. To find more information about your wholesaler, follow the link here

How do I get a Trade Effluent Consent?

Wholesale Water and Sewerage Companies (WaSCs) will have information on their websites that should include links to downloadable or embedded application forms.   There will usually be an associated application fee.  NWL Application For A Consent to Discharge Trade Effluent

The application process

Generally, each wholesaler will ask for similar information, and you can see the key things to consider below.   Please be aware though, that each wholesaler will have their own forms for you to complete, so it’s worth taking the time to get the right one. 

Once you have the form, you’ll need:

  • Details about your Company,
  • 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. 

Our account management team may be able to provide some hints and information, but if you need help with a particular section, please contact your Wholesaler.

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 will pay particular attention to ensure 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.

Appeals can be made to Ofwat regarding any refusal by the Wholesaler to grant Consent or regarding any consent condition a wholesaler seeks to impose.

How is Trade Effluent checked?

Your Consent may contain conditions for self-monitoring your effluent discharge, in terms of flow or composition.  The Wholesale business 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?

Wholesale companies use several different mechanisms to charge their Trade Effluent customers but basically it will fall into one or more of the categories below.

  1. It is all charged as domestic 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 is 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)

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. 

 

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