If your business washes vehicles on company premises — whether with a hose, a pressure washer, or a bucket — you may be breaking the law. The Water Industry Act 1991 classifies vehicle wash water as trade effluent, and discharging it into the drainage system without consent from your water company is a criminal offence.
Most UK businesses are completely unaware of this obligation. Here is what you need to know.
What Is Trade Effluent?
Trade effluent is any liquid waste discharged from business premises into the public sewer, other than domestic sewage. Under Section 118 of the Water Industry Act 1991, discharging trade effluent without a consent (also called a trade effluent discharge consent) from your local water and sewerage company is prohibited.
Vehicle wash water is classified as trade effluent because it contains:
- Detergents and cleaning chemicals
- Heavy metals from brake dust (copper, zinc, lead)
- Petroleum hydrocarbons from engine and road residues
- Suspended solids from road grime and tyre compounds
These contaminants make vehicle wash water significantly different from domestic wastewater, which is why it requires separate consent.
Who Does This Affect?
Any business that washes vehicles on its premises using water. This includes:
- Companies that allow employees to wash company cars in the car park
- Fleet operators that hose down vehicles at depots
- Businesses that hire mobile valeting services using water-based methods
- Facilities where contractor vehicles are washed on-site
If water contacts a vehicle on your premises and then enters the drainage system — whether via a drain, gully, or surface water runoff — you may need trade effluent consent.
The Consequences of Non-Compliance
Discharging trade effluent without consent can result in:
- Prosecution by the water company or the Environment Agency
- Fines — which can be substantial for repeat offences
- Remediation costs if contamination is identified
- Reputational damage — particularly problematic for businesses with ESG commitments
Even if enforcement action is rare, the risk is real — and entirely avoidable.
How to Obtain Trade Effluent Consent
If you need to wash vehicles with water on your premises, you must:
- Apply to your local water and sewerage company for a trade effluent discharge consent
- Demonstrate that you have appropriate interceptor systems (oil separators, settlement tanks) to treat the wastewater before it enters the sewer
- Pay ongoing charges for the trade effluent discharge
- Submit to monitoring and inspection by the water company
This process involves capital expenditure for interceptor installation, ongoing operating costs, and administrative burden.
The Waterless Alternative
Waterless fleet valeting eliminates the entire trade effluent question. No water is used in the cleaning process, which means:
- No wastewater is generated — nothing enters the drainage system
- No trade effluent consent is required — removing the legal obligation entirely
- No interceptor infrastructure is needed — saving capital expenditure
- No ongoing discharge charges — reducing operating costs
For businesses that operate from leased premises (where installing interceptors may not be permitted by the landlord), waterless valeting is often the only compliant option for on-site vehicle cleaning.
MMCC: Compliant Fleet Care by Design
MMCC’s waterless fleet valeting is Water Industry Act compliant by design. Zero water usage means zero trade effluent, zero drainage impact, and zero regulatory risk.
Every service is documented with environmental data that confirms zero water usage — evidence your compliance team can reference in audits and regulatory submissions.