Tom Melhuish 8 min read

Trade Effluent charges, everything you need to know as a business

Here at AquaSwitch, our mission is to make the water industry more understandable for British businesses. A subject that causes endless confusion for business owners is trade effluent charges. This guide clarifies what trade effluent is, producers’ responsibilities, and how it impacts business water bills.

Trade effluent, everything you need to know as a business

First, it’s worth a quick explanation of how the sewerage network works in the UK.

The regional water wholesalers manage a network of pipes that transfer wastewater away from all properties in the UK. Wastewater includes both rainwater landing on the properties as well as sewage produced by human activities.

The network of pipes, known as sewers, transports this wastewater to a local treatment facility where it is cleaned to a standard where it can be returned to a reservoir.

Businesses will typically produce domestic sewage from flushing toilets and draining sinks. The removal of domestic sewage will be charged to your business as a fixed charge for the maintenance of the sewerage network and a volumetric wastewater charge based upon the amount of domestic sewage removed.

Trade effluent is where your business disposes of any substance into the sewers that are not domestic sewage.

The water wholesalers carefully manage trade effluent as it is necessary to ensure that all contaminants in the sewage system are appropriately treated before being returned to the water cycle.

What is trade effluent?

Trade effluent is any liquid produced in a business property by a trade or production activity.

Trade effluent is most easily understood as anything that goes into your drain that isn’t domestic sewage. Here are some examples:

Trade effluent produced in consumer services

  • The water drained from a local car wash that includes cleaning products
  • The wastewater from a commercial launderette that includes detergents
  • The water drained from a swimming pool that includes chlorine

Trade effluent produced in production activities

  • Liquid waste from the production of food and drinks
  • Waste products from the production of pharmaceuticals
  • Water used by power stations in the production of electricity

What are my responsibilities with trade effluent?

It is essential for the health of the population and the wider environment that trade effluent is carefully managed and treated by the water wholesalers.

The key responsibility of business is to ensure that you have gained consent for any trade effluent being produced by your trade. The Water Industry Act 1991 sets out this requirement for consent, and it is a criminal offence to produce trade effluent without permission.

If you are currently producing trade effluent without consent, you must immediately contact your water supplier, who will talk to the wholesaler on your behalf.

The local water wholesaler that manages the sewerage network is responsible for issuing consent to properties in their region.

The consent given by your wholesaler will contain several specific conditions to limit the volume and quantity of contaminants in the trade effluent. If a business does not adhere to the limits of the consent, it is an offence under section 121 of the Water Industry Act 1991.

What is trade effluent consent?

Trade effluent consent is a legal document issued by your regional water wholesaler giving your business the consent to discharge trade effluent into the sewers within the limits of specified criteria.

A trade effluent consent, when granted, will include the following restrictions and specifications:

Premises – Defines the property from which the trade effluent is produced.
Sewer affected – Defines the sewer which the trade effluent is being disposed.
Dates – Defines a commencement date of the consent and an end date if a temporary consent.
Maximum quantity – The maximum volume of trade effluent to be discharged in any 24 hours.
Maximum rate – The maximum rate of discharge of trade effluent
Eliminated substances – Any substances which must be removed from the trade effluent prior to discharge
Temperature limit – A maximum temperature of the trade effluent when discharged into the sewers.
pH limits – An allowable range of acidity and alkalinity of the trade effluent on discharge.

Trade effluent consents are a publically available document that is recorded on a register maintained by the wholesalers.

Are there any exceptions to needing trade effluent consent?

The discharge of domestic sewage into the sewerage system does not require trade effluent consent. This is the case even if it is a business premise that is producing domestic sewage.

Domestic sewage includes wastewater from:

  • Toilets
  • Personal washing, showering and bathing
  • Commercial cooking for sale directly to consumers, such as a restaurant or sandwich bar
  • Washing dishes and cooking equipment, on a scale comparable to domestic cooking, after using them on the premises

The government has issued specific guidance on what qualifies and does not qualify as domestic sewage here.

How do I get trade effluent consent?

A trade effluent consent application is submitted to your water supplier, who will work with the local wholesaler to process your application.

The trade effluent application consists of one of the following two forms:

The non-household market operator provides guidance on how to fill out these consent applications in the following guides:

What happens if I’m refused consent?

The water wholesalers have the right to refuse a trade effluent consent application on the basis that:

  • The trade effluent will cause undue harm to the environment
  • The trade effluent will damage the sewage system
  • The local treatment plant will not be able to process the trade effluent

If your business is refused consent to discharge trade effluent in the public sewers, then there are several alternative options, including:

  • Using a disposal firm to take the effluent away and treat it for you.
  • Treating the trade effluent at your business property to change it to a state that would be suitable for disposal in the public sewer network.
  • Altering your business operations such that the effluent is suitable for disposal in a public sewer.

What are trade effluent charges?

Businesses that dispose of trade effluent in the sewerage system are charged for the treatment of this waste.

The regional water wholesaler who manages the sewerage network will calculate a charge based explicitly upon the volume and nature of the effluent produced by each property separately.

Your business water supplier will then pass on these charges, plus a retail fee, to your business.

On a business water bill, these will be presented separately from the domestic wastewater charges.

How much will my trade effluent bill be?

The regional water wholesalers who maintain the sewerage network and waste treatment plants determine how much they will charge businesses to dispose of trade effluent. Each of the regional wholesalers publishes how they determine the trade effluent charge in their annual scheme of charges.

The regional wholesalers in England and Scotland refer to the ‘Mogden formula’ in calculating their trade effluent charge. This complex formula attempts to unify the calculation of charge for a wide variety of forms of trade effluent.

What is ‘The Mogden Formula’?

The Mogden Formula is:

Charge per unit of effluent = R + [(V + Bv) or M] + B(Ot/Os) + S(St/Ss)^7

R = reception and conveyance charge [p/m3]
V = primary treatment (volumetric) charge [p/m3]
Bv = additional volume charge if there is biological treatment [p/m3]
M = treatment and disposal charge where effluent goes to sea outfall [p/m3]
B = biological oxidation of settled sewage charge [p/kg]
Ot = Chemical oxygen demand (COD) of effluent after one hour quiescent settlement at ph 7
Os = Chemical oxygen demand (COD) of crude sewage one hour quiescent settlement
S = treatment and disposal of primary sewage sludge charge [p/kg]
St = total suspended solids of effluent at ph 7 [mg/litre]
Ss = total suspended solids of crude sewage [mg/litre]

The Mogden formula necessarily includes lots of chemical measures to determine the strength of trade effluent. In more simple terms, the Mogden formula says that trade effluent charges will equal the amount of trade effluent discharged multiplied by the strength of the trade effluent.

Next, let’s look at the individual components of the trade effluent charge.

What factors influence the trade effluent charge?

i. Reception and conveyance

The wholesaler levies this charge for accepting trade effluent and transporting it to a treatment centre through the sewerage network. The charge usually comes in two parts:

  • A fixed charge if you have active trade effluent consent at a property.
  • A volumetric charge for each cubic meter of trade effluent discharged into the sewer.

ii. Treatment charges

This charge is for treating the trade effluent, a process in the water cycle that cleanses the sewerage water before going back into the clean water reservoirs. There are several components to this charge:

  • A volumetric charge for the treatment of each cubic meter of trade effluent processed through the treatment centre.
  • A biological treatment charge – This is a charge levied for the process of biological treatment of the trade effluent at the treatment plant. The charge depends on the chemical oxygen demand of the trade effluent (a measure of how strong the trade effluent is). The stronger the effluent, the higher this charge will be.

iii. Sludge disposal

The treatment of trade effluent produces a sludge of pollutants that is separated from the clean water. Trade effluent charges include a specific charge for the disposal of this sludge. The charge is levied based upon the weight of the sludge produced from treating the trade effluent your business produces.

Trade effluent monitoring

Your water wholesaler will regularly take samples of your trade effluent discharge to ensure that your business is adhering to the consent and collecting the composition data to allow them to charge your business accurately.

A condition of your consent document will be that you provide an access point to the trade effluent discharge to collect samples.

Depending on the nature of your trade effluent, your business may be required to install a method of monitoring your effluent discharge. A monitoring system is recommended as it allows your business to ensure adherence to the trade effluent consent and be informed of any issues as they arise.

How to reduce trade effluent charges

Your business can take active steps to reduce your trade effluent charge; our biggest recommendations are:

  • Comparing trade effluent charges from different suppliers. Business water suppliers will often add a retail fee to any trade effluent charges levied against your business. See if your business can benefit from switching water suppliers.
  • Installing an effluent treatment system that reduces the intensity of your trade effluent. Through the Mogden formula, if your trade effluent is less strong you will be billed less.
  • Installing a trade effluent monitoring system so that any reductions in volume or intensity of trade effluent can be measured and the water supplier informed.

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