Case file
Warm fat looks harmless going down. It cools, hardens, coats the pipe and binds everything that follows - and the bill arrives four ways: blocked drains, pests and smells, a criminal offence under s111, and waste rules broken for the price of a collection fee.
Case file
It starts as a slow sink during Saturday service and ends, in the version water companies now prosecute, with sewage backing up a neighbouring street and an investigator tracing hardened fat up the lateral to one kitchen's drain. Warm fat looks harmless going down; it cools, hardens, coats the pipe and binds everything that follows. Every kitchen that fries, roasts or washes up sends some of it that way - the question is only how much, and whose pipe it solidifies in.
What it actually costs
The first bill is your own drainage: FOG solidifies in the kitchen's pipes long before the public sewer, so the habit buys emergency call-outs, jetting, and services lost to a sink that will not drain on the busiest night of the week - and drainage emergencies price like emergencies, out of hours, per visit, with the lost covers on top. Repeated blockages despite cleaning are the signature - the deposit survives each clear-out and regrows faster as the bore narrows, so each call-out buys a shorter reprieve than the last. The second bill is biological: a greased drain is a food supply, which is why drain flies colonise exactly the kitchens with FOG problems, and why persistent smells and damp, mould-friendly corners follow blocked or weeping pipework.
The third bill is legal. Under section 111 of the Water Industry Act 1991 it is a criminal offence to discharge anything into a public sewer that interferes with the free flow of wastewater - and water companies use it against food businesses, escalating from warning letters and action plans to prosecution, with clearance costs recharged on top. One restaurant received the maximum Magistrates' fine after ignoring exactly that escalation; the judgment noted a small grease trap would have prevented the whole affair. The fourth bill is the quietest: waste cooking oil is controlled waste under the Environmental Protection Act 1990, so disposing of it down the drain instead of through a licensed carrier saves a modest collection fee and creates evidence of an offence at the same time.
The fix
None of this is exotic, which is rather the point the prosecutions keep making: the fix costs less than one emergency call-out, and immeasurably less than the letter. It is also cumulative - a kitchen that scrapes, strains and collects has drains that stay clean for years, while one that does none of it re-buys the same blockage on a shortening cycle.
Questions
If it interferes with the flow of the public sewer - which FOG reliably does - it is an offence under section 111 of the Water Industry Act 1991, with fines up to GBP 50,000 in a Magistrates' Court, unlimited in the Crown Court, and clearance costs recharged. Waste cooking oil is also controlled waste, so it must go to a licensed carrier with transfer notes kept for two years.
No single UK law mandates one by name, but the responsibility for the outcome is legal either way: s111 makes blocking the sewer an offence, and water companies expect effective FOG control from food businesses, escalating enforcement where it is absent. In one prosecution the court noted a small grease trap would have prevented the offence entirely. New fit-outs should design grease management in from the start - retrofitting is always dearer.
Because jetting clears the channel but the hardened FOG lining survives, so the bore is permanently narrowed and each new discharge sticks faster. Repeated blockages despite routine cleaning are the classic sign of an established grease deposit - a CCTV survey will show it - and the lasting fix is stopping fat at source: scraping, strainers, oil collection and a maintained trap.
No - it just relocates the problem. Hot water keeps fat liquid for the first few metres; it hardens again at the first cool section of pipe, often deeper in the run or in shared pipework where it is harder and dearer to reach. Detergent emulsifies fat briefly with the same downstream result. The only reliable approach is keeping FOG out of the water in the first place.
Phoenix Duct Clean · by the numbers
The fat that blocks the drain also loads the ductwork. TR19 Grease cleaning keeps the airborne half certificated and off your risk register.