Grease trap: what is a grease trap and what are grease traps, how does a grease trap work and how do grease traps work, the grease trap uk and grease traps uk rules, and what grease trap regulations uk put on a commercial kitchen

How grease traps and liquid waste works

1. Understand what the duty actually is. The Water Industry Act makes it an offence to discharge into a public sewer any matter likely to interfere with its free flow. Water companies apply that to fats, oils and grease from catering premises, and a trade effluent consent or the company's own FOG policy sets what they expect on your site.
2. Establish what the site already has. Under sink units, external below ground traps, and automatic grease recovery units are all in use, and many kitchens have one nobody has opened. Finding it, and finding when it was last emptied, is the first job on almost every premises.
3. Size it to the kitchen, not to the cupboard. Capacity follows the flow from the appliances discharging into it and the retention time needed to separate. A unit chosen because it fitted the space under the sink will overflow into the drain during service, which is the failure mode environmental health and the water company both see.
4. Put the emptying on a schedule. A trap only works while there is room in it. Frequency follows the volume of covers and the type of cooking rather than a calendar rule, and a contractor will set it after seeing the site and adjust it once the first few visits show how fast it fills.
5. Keep the paperwork. The grease and the waste oil leaving the premises are waste, and the duty of care applies: a registered carrier, a waste transfer note for each collection, and records kept. That file is what the environmental health officer, the water company and the landlord all ask for.

Paperwork and evidence

Common questions

Is a grease trap a legal requirement in the UK?

No regulation names one directly. What is unlawful is discharging matter likely to harm the sewer, and water companies and local authorities expect catering premises to fit and maintain suitable grease management, which in practice means a trap or a recovery unit.

Who enforces it?

The water company for the sewer, the local authority's environmental health service for the premises, and increasingly landlords through the lease. All three ask for the same evidence.

Does this site empty grease traps?

No. This is an introducer: the enquiry goes to a licensed liquid waste contractor who services the trap and takes the waste away under a transfer note.

What happens if grease reaches the sewer?

Blockages on your own drainage first, then the shared sewer. Water companies recover the cost of clearing blockages traced to a premises, and prosecution is available where discharge continues.

Licensed contractors by county