101: Fat, Oil and Grease Regulations in the UK
Fat, oil and grease — usually called FOG — is one of the biggest causes of drain and sewer blockages in foodservice. For restaurants, pubs, hotels, hospitals, schools, takeaways and commercial kitchens, the legal position is simple:
You must not allow FOG from your kitchen to enter the drainage system in a way that blocks, damages or interferes with the sewer network.
That duty comes from several pieces of UK legislation and guidance.
1. Water Industry Act 1991 — the main legal risk
The most important law is Section 111 of the Water Industry Act 1991.
It makes it an offence to discharge, or allow to be discharged, anything into the public sewer that may interfere with the free flow of wastewater. Fats, oils and grease are specifically treated by water companies as a major risk because they solidify, stick to pipework and cause blockages.
In practice, this means a food business can be held responsible if FOG from its premises contributes to a blockage, sewer flooding, pollution incident or damage to the network.
Possible consequences include:
- Enforcement action from the local water company.
- Requirement to install or improve grease management.
- Drain clearance and repair costs.
- Prosecution.
- Potentially unlimited fines in serious cases.
2. Building Regulations — grease separation in commercial kitchens
The key guidance is Approved Document H: Drainage and Waste Disposal, section 2.21.
It states that drainage serving kitchens in commercial hot food premises should be fitted with:
a grease separator complying with BS EN 1825, designed in accordance with BS EN 1825-2, or other effective means of grease removal.
This is important because it does not only point to one type of product. It recognises either:
- A passive grease separator.
- A grease removal unit.
- Another effective grease management system.
But the system must be suitable, correctly sized, installed properly and maintained.
3. BS EN 1825 — the recognised standard for grease separators
BS EN 1825 is the European/British standard commonly referenced for grease separators.
In simple terms, it covers how grease separators should be designed, sized and used. For larger commercial kitchens or new-build/refurbishment projects, consultants, building control officers, landlords and water companies may refer to BS EN 1825 when deciding whether a system is appropriate.
The key point is that equipment should not just be “a grease trap”; it should be suitable for the kitchen’s flow rate, use, menu, cleaning regime and risk level.
4. Environmental Protection Act 1990 — waste duty of care
FOG waste removed from a grease trap or grease recovery unit is controlled waste. Under the Environmental Protection Act 1990, businesses have a duty of care to make sure waste is handled, stored, transferred and disposed of correctly. Thames Water also notes that businesses should keep records where kitchen waste is collected, so they can show that the contractor is licensed and registered.
In practice, this means you should:
- Use a licensed waste carrier.
- Keep waste transfer notes.
- Keep service and collection records.
- Avoid pouring waste oil, grease trap contents or food waste into drains.
5. Food Safety Act 1990 and hygiene inspections
Local authorities can inspect food premises under food safety legislation. FOG issues can quickly become hygiene issues because blocked drains, bad smells, pests, overflowing grease traps and contaminated wash areas can affect food safety.
Anglian Water’s FOG guidance links local authority inspection powers with the Food Safety Act 1990 and explains that poor FOG disposal can lead to enforcement where it creates hygiene or drainage problems.
6. What food businesses are expected to do
A food business should be able to show that it has a working FOG management system. That usually means:
Install suitable equipment
Use a grease separator, grease recovery unit or other effective means of grease removal.
Maintain it properly
A grease trap that is never emptied or cleaned is not compliance. It becomes part of the problem.
Train kitchen staff
Staff should know not to pour fat, oil, gravy, sauces, dairy, stock or food waste down the sink.
Use good kitchen practices
Scrape plates, use sink strainers, dry-wipe pans before washing, and collect waste oil separately.
Keep records
Service logs, cleaning schedules, waste transfer notes and contractor records are important if there is an audit, blockage or dispute.
7. Common misconception: “I only need a grease trap if the water company tells me”
Not quite.
A business may come under pressure from several directions:
- The water company under the Water Industry Act.
- Building control during construction or refurbishment.
- The landlord through lease obligations.
- Environmental health during inspections.
- Insurers after a flood or blockage.
- The customer or facilities team in a multi-site estate.
So even if a site has not yet been visited by the water company, it still has a duty to prevent FOG entering the drainage system.
8. Simple compliance checklist
A good “FOG compliance file” should include:
AreaEvidence to keepEquipmentSpecification, sizing, installation recordMaintenanceCleaning/service logsWasteWaste transfer notes and licensed carrier detailsStaff trainingTraining records or toolbox talk sheetsDaily checksKitchen cleaning and FOG control checklistIncidentsBlockage reports and corrective actions
9. Plain-English summary
For foodservice operators, FOG compliance means:
Do not let fat, oil and grease go down the drain. Install an effective grease management system, maintain it, train staff, and keep records to prove it.
The legal risk mainly comes from Section 111 of the Water Industry Act 1991, while Building Regulations Approved Document H points commercial hot food premises toward a BS EN 1825 grease separator or other effective means of grease removal. Waste removed from the system must then be handled correctly under environmental duty-of-care rules.
