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Trade effluent - businesses
Trade effluent is any liquid waste discharged into our sewers from a business or industrial process on a trade premises.
For non-household customers, your retailers should be your first point of contact. For more information on how you choose your retailer, please visit the Open Water website.
Understanding trade effluent
What is it?
Section 141 of the Water Industry Act 1991: Trade effluent is any liquid waste, with or without suspended particles, produced wholly or partly from trade or industrial activities on trade premises. Including wastewater from production processes, washing, cooling, and public-funded activities like municipal landfills. It excludes domestic sewage (toilet, bath, or sink waste) and uncontaminated rainwater.
Examples of trade effluent sources:
- Commercial car washes
- Laundries/launderettes
- Food and drink production
- Chemical manufacturing
Why control it?
We need to control trade effluent to ensure that any matter that may cause harm is not discharged.
Trade effluent is highly variable in strength and volume and may contain substances that are a risk to people, our sewerage network, treatment processes and the environment. Controls are in place to reduce these risks.
Under Section 111 of the Water Industry Act 1991, it is an offence to discharge any matter likely to cause harm, this includes fat, oils and grease (FOG) in food businesses.
What happens to it?
Large solids are first removed, followed by a settlement process that extracts heavy waste as sludge for treatment and recycling.
Biological treatment then removes organic contaminants using bacteria and microbes.
A final settlement stage (clarification) eliminates remaining waste particles. In some cases, further treatment is needed for stricter discharge limits, such as nutrient-sensitive waters.
The treated effluent is released back into the environment to continue the cycle. It can also be purchased for industrial or business use.