Phoenix Journal · Kitchens
Water industry law treats a blocked public sewer as your problem the moment it can be traced back to your kitchen. Here is what the byelaws and the Water Industry Act actually ask of a commercial food business, and how to stay on the right side of them.
Compliance & drainage
If a water company can prove the fat blocking a public sewer came off your site, the law is squarely on their side - and the bill can land on your doorstep.
Most kitchen managers meet the water industry rules the hard way: a letter arrives, a jetting crew has been out, and someone wants paying. It does not have to go that way. The framework that governs what leaves your drains is old, settled and fairly plain once you strip out the jargon. The headline duty comes from section 111 of the Water Industry Act 1991, which makes it a criminal offence to let anything into a public sewer that is likely to injure the sewer, interfere with the free flow of its contents, or harm the treatment works downstream. Fats, oils & grease sit right at the top of that list.
Layered on top are the local byelaws and trade effluent conditions your water and sewerage company sets, the drainage provisions in the Building Regulations, and the Water Supply (Water Fittings) Regulations 1999 that protect the mains coming in. None of it is exotic. The steps below walk through what each one asks of a working kitchen, in the order you would sensibly tackle them.
Water companies are far better at tracing blockages than they once were. When a crew clears a fatberg, they can survey the sewer, work back to the connections feeding it, and identify the run of premises responsible - and a kitchen that discharges visible grease is not hard to spot. Sewer blockages already cost the industry a great deal to clear; British Water has put the figure at more than £80 million a year, and the large majority of those blockages involve fat, oil and grease. That is money the companies are increasingly willing to chase back to source.
There is a public-health edge to it too. As trapped FOG breaks down in a drain it turns anaerobic and gives off hydrogen sulphide - H₂S - the gas behind that unmistakable rotten-egg drain smell. It is corrosive to pipework and unpleasant for everyone working near it, which is why a fatty drain is usually the first sign of a compliance problem rather than the last. If your kitchen has reached that stage, it is worth reading up on why kitchen drains start to smell before the odour turns into a blockage notice.
The financial exposure is not limited to fines and clearance costs either. A site that keeps causing sewer problems can find itself facing trade effluent scrutiny and rising charges, and a drain that is not flowing freely is often a drain that is quietly inflating what you pay. If your figures have crept up, it is worth checking why a water bill can end up higher than it should be, because poor grease management and inflated charges frequently travel together. None of this is about catching operators out - the rules reward the kitchens that keep their grease under control and penalise the ones that let it wash away and become someone else's flood.
Compliance with the water industry byelaws is not a one-off certificate; it is a routine. Correctly specified grease separation, a realistic cleaning schedule, tidy records and a quick response when a water company makes contact will keep almost any kitchen clear of section 111 trouble. The businesses that come unstuck are rarely the ones that tried and failed - they are the ones that fitted a trap years ago and never looked at it again.
A deep clean of the extraction and drainage system is the natural moment to put all of this right. It clears the grease that has already built up, exposes any separator that is undersized or neglected, and gives you a documented baseline to work from. From there, keeping to the schedule is straightforward, and the drains stop being a liability you worry about every time it rains.
Questions
Yes. Section 111 of the Water Industry Act 1991 is a strict-liability offence, so the water company only has to show the offending discharge came from your premises - not that you meant any harm. If they have spent money clearing a blockage or dealing with flooding, they can also pursue you to recover those costs on top of any fine.
In practice, yes. The Building Regulations Part H expect drainage from a hot-food kitchen to include an effective means of grease removal, and the recognised standard for grease separators is BS EN 1825. Without one, grease reaching the public sewer puts you in breach of section 111, so a correctly sized and maintained separator is the sensible way to comply.
Respond quickly rather than ignoring it. The letter means they have traced a drainage problem to your site, and silence tends to push matters toward prosecution or cost recovery. Get your grease management reviewed, arrange a deep clean of the drains and separator, and confirm the fix to them in writing so there is a clear record you acted.
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