What is Trade Effluent? UK Consent Rules, Compliance Obligations and On-Site Storage as an Alternative
More than 300,000 businesses in the UK discharge liquid waste from industrial and commercial processes to the public sewer every year. For the majority of those businesses, that discharge is not simply wastewater. It is trade effluent, and it is subject to a separate legal framework that sits entirely apart from the rules governing ordinary domestic sewage. Getting this wrong is not a minor administrative issue. Discharging trade effluent without consent from your sewerage undertaker is a criminal offence under the Water Industry Act 1991, and the consequences range from enforcement notices to unlimited fines and prosecution.
Businesses operating off the mains sewer, or those managing large volumes of industrial liquid waste, often find that on-site containment in a corrugated steel water storage tank is a more practical and cost-effective approach than navigating the consent process entirely. This guide covers everything you need to know: what trade effluent is, who it applies to, how the consent process works, what charges to expect, and when on-site storage is the right solution for your site.
What is Trade Effluent?
Trade effluent is any liquid waste, other than domestic sewage or uncontaminated surface water, that is discharged from premises used for a trade or industrial process. The key phrase is "trade or industrial process." If the liquid is produced as part of a manufacturing, processing, cleaning, or treatment operation carried out at your premises, it is trade effluent regardless of how diluted it is or how harmless it may appear.
The definition is deliberately broad. It covers liquid waste from food production, metal finishing, vehicle washing, pharmaceutical manufacturing, laundry and laundrette operations, and any other industrial process that produces liquid as a byproduct or waste stream. Even relatively benign effluent such as cooling water or rinsing water from a production line falls within the definition if it originates from a trade or industrial process.
For businesses handling large volumes of industrial liquid, the choice of containment matters as much as the consent process. The liner kit inside any storage tank must be chemically compatible with the specific effluent being stored, whether that is acidic process water, hydrocarbon-contaminated runoff, or high-strength food production waste. Getting the liner specification right from the start prevents costly failures and compliance breaches.
What is not trade effluent is equally important to understand. Domestic sewage from toilets, sinks, and kitchen facilities on the same premises is not trade effluent. Uncontaminated surface water that has not come into contact with any trade process is not trade effluent. The distinction matters because domestic sewage can be discharged to the public sewer without consent, while trade effluent cannot.
Common examples of businesses that produce trade effluent include car washes, takeaways and caravan parks, metal finishing operations, food processing facilities, industrial laundries, and any premises where chemicals, greases, and food waste enter the drainage system as part of the trade being carried on.
The Water Industry Act 1991 and Why It Governs Trade Effluent
The legal framework for trade effluent in England and Wales is set out in the Water Industry Act 1991. Under this legislation, no business may discharge trade effluent to the public sewer without first obtaining consent from the sewerage undertaker responsible for that sewer. The sewerage undertaker in your area is typically a regional water company such as Thames Water, Severn Trent, or United Utilities.
The Act places the full responsibility to obtain consent prior to commencing any trade effluent discharge on the occupier of the premises. It does not matter whether you own the building, lease it, or have recently taken it over. The consent obligation falls on whoever is carrying on the trade at the time of discharge. Responsibility to obtain consent prior to commencing operations is non-negotiable, and "I did not know" is not a recognised legal defence.
For sites where the consent process is lengthy or where consent has been refused, professional installation of an on-site containment system by a specialist team gives businesses a compliant interim or permanent solution while their regulatory position is resolved. Butek Tanks designs and installs trade effluent containment systems across the UK, typically within days rather than the weeks or months a consent application can take.
The Act also gives sewerage undertakers the power to impose conditions on any consent they grant, to vary those conditions, to levy charges for receiving and treating the effluent, and to refuse consent entirely where the effluent would damage the sewer network or the sewage treatment works downstream.
Who Needs to Apply for Trade Effluent Consent?
Any business that discharges, or intends to discharge, trade effluent to the public sewer needs to apply for trade effluent consent before that discharge begins. There are no volume thresholds that exempt small businesses. The obligation applies equally to a small car wash discharging a few hundred litres a day and a large industrial facility discharging thousands of cubic metres.
The question of whether your liquid waste is classed as trade effluent is one your sewerage undertaker will assess based on what your premises are used for and what processes produce the discharge. If you are unsure whether your discharge requires consent, contact your sewerage undertaker before commencing any trade effluent discharge. Discharging first and asking later is the most common and most costly mistake businesses make.
Businesses that have changed use, expanded their operations, or taken on new industrial processes should review their existing consent. A consent granted for one type of effluent does not automatically cover additional or different discharges from new processes introduced later.
How to Apply for Trade Effluent Consent
The application process is managed by your local sewerage undertaker. You will need to provide details of the nature of the trade effluent, its likely volume and flow rate, the hours during which discharge will take place, the point of discharge to the sewer, and any pre-treatment you intend to carry out on-site before discharge.
Your sewerage undertaker will assess the application against the capacity of the receiving sewer and the sewage treatment works. If the effluent contains materials such as chemicals, heavy metals, or other substances that could damage the sewer infrastructure or affect sewage treatment processes downstream, the undertaker may impose conditions or refuse consent. If your application is unsuccessful, you must either modify your process, provide additional pre-treatment, or consider alternative arrangements for managing your effluent on-site.
Site drainage plans and safety data sheets for any chemicals used in your process will typically be required as part of the application.
Trade Effluent Consent Conditions and Charges
When consent is granted, it comes with conditions. These typically specify the maximum volume of trade effluent you may discharge, the permitted hours of discharge, the maximum concentration of specific substances, pre-treatment requirements, and monitoring and record-keeping obligations.
Trade effluent charges are a separate matter from the consent itself. Sewerage undertakers charge for receiving and treating trade effluent based on the volume and strength of the discharge. Most undertakers in England and Wales use the Mogden formula to calculate charges. The Mogden formula accounts for the volume of the discharge, its chemical oxygen demand, and its suspended solids content. The stronger and more voluminous your discharge, the higher the charge. For high-strength industrial effluent, trade effluent charges can represent a significant and ongoing operating cost that makes on-site storage and offsite disposal by a licensed waste carrier a commercially attractive alternative.
The Offence of Discharging Without Consent
Discharging trade effluent to a public sewer without consent, or in breach of consent conditions, is a criminal offence under the Water Industry Act 1991. The sewerage undertaker may issue enforcement notices, apply for injunctions, and bring criminal prosecutions. Businesses found discharging in breach of their consent conditions are subject to legal action, and individual directors can be personally liable in serious cases.
The offence applies regardless of whether the effluent actually causes harm to the sewer or the environment. The act of discharging trade effluent without the necessary consent or in breach of conditions is itself the offence. Enforcement has become more rigorous as pressure on sewage treatment infrastructure has increased across the UK in recent years.
When On-Site Storage is the Right Solution
For many commercial and industrial sites, obtaining trade effluent consent and managing an ongoing discharge is the right approach. But there are circumstances where on-site containment and storage before disposal by a licensed waste carrier, or pre-treatment before discharge, is more practical and cost-effective.
If your application is refused because the effluent is too strong or incompatible with the receiving sewer, you need an alternative. If your site is remote and not connected to a public sewer, consent-based discharge is not an option. If your effluent volumes are highly variable with periodic surges from production processes, on-site storage provides a buffer that enables controlled, compliant discharge rather than unmanaged peaks.
Our corrugated steel storage tanks, fitted with chemically resistant liner kits such as the Landflex ES liner, provide high-capacity, structurally certified containment for trade effluent and industrial liquid waste. Tanks are available from 2m3 to 5,000m3 and can be deployed on-site without extensive groundworks. A full range of accessories including inlet and outlet valves and pump connections are available for every tank configuration.
For sites requiring treatment before storage or discharge, our Modular Wastewater System (MWS) provides a complete, deployable treatment solution installable in as little as 7 to 20 days, producing treated water that is 99.99% pathogen-free and suitable for discharge directly to an existing drainage system.
Frequently Asked Questions About Trade Effluent
What is the difference between trade effluent and domestic sewage?
Domestic sewage is wastewater from toilets, sinks, baths, and kitchen facilities used for ordinary domestic purposes. Trade effluent is liquid waste produced by a trade or industrial process. Both may be present at the same site, but only domestic sewage can be discharged to the public sewer without consent. Trade effluent requires a separate consent from the sewerage undertaker under the Water Industry Act 1991.
Does trade effluent consent cover all liquids from my site?
No. Trade effluent consent covers only the specific discharge it was granted for. If you introduce new processes, new chemicals, or increase your discharge volume beyond the conditions of your consent, you must apply to vary your consent. Discharging anything other than domestic waste that falls outside your consent conditions is an offence.
Can on-site storage replace trade effluent consent?
On-site storage does not replace the consent requirement if you are discharging to the public sewer. However, if you are storing effluent for collection by a licensed waste carrier rather than discharging to the sewer, consent is not required for the storage itself. For sites where sewer connection is not viable, on-site containment followed by licensed collection and offsite treatment is a fully legal alternative.
What is the Mogden formula?
The Mogden formula is the calculation used by most sewerage undertakers in England and Wales to determine trade effluent charges. It takes account of the volume, chemical oxygen demand, and suspended solids content of the discharge. Businesses with high-strength or high-volume discharges typically face the highest charges under the formula, which is one reason on-site pre-treatment before discharge is commercially attractive.
Need Large-Scale Trade Effluent Storage or Treatment? Butek Tanks Can Help
Whether you are managing high-strength industrial effluent, responding to a refused consent application, or operating a site with no sewer connection, Butek Tanks has the expertise to deliver the right storage or treatment solution quickly. As a specialist division of Butyl Products Ltd, we design, manufacture, and install corrugated steel storage tanks for trade effluent, industrial wastewater, and liquid waste applications across the UK and internationally. Our solutions are ISO 9001:2015 certified, CE marked, and deployable globally.
Get in touch today. Call us on +44 (0)1277 653 281 or email enquiries@butektanks.co.uk, or visit our contact page to submit your project requirements. Our team will respond promptly to discuss your needs.