Drain Rats in Commercial Premises

Why commercial is different

Three Things

Grease. A kitchen system carries fats and oils that cool and deposit on the pipe wall, narrowing the bore and holding solids. That creates standing, food-rich conditions in the drainage itself — a reason for rats to stay rather than pass through — and it makes surcharge likelier, which stresses joints that were fine under normal flow.

Scale and complexity. More fittings, more branches, more chambers, often more than one connection to the sewer, and frequently alterations made by successive tenants that nobody recorded.

Nobody lives there. A domestic drain problem gets found because somebody is lying in bed above it. A commercial one runs until it produces a smell, a blockage or a sighting in front of a customer.

What an inspector looks for

Knowing, and Showing

For food premises the question is not whether you have ever had rats — a town-centre kitchen with a yard and a bin store is exposed by its nature — but whether you knew, what you did, and whether you can show it.

So the useful output of drainage work here is the record as much as the work: what was surveyed, what was found and where, what was fitted, what was recommended, and what remains outstanding. A survey recording and a fault list are exactly the sort of evidence that turns a finding into a closed item.

Proofing recommendations matter too, because "we were advised to seal three pipe entries and here is the invoice" is a much better position than "we didn't know".

The yard

Where It Usually Comes From

Kitchen drainage gets the attention; the yard is where the problem usually lives.

• Gullies and open channels, which are a way into the system from above and a place for waste to sit.
• Chambers with broken or missing covers, which are an open door into the drainage. Surprisingly common in a busy yard.
• Bin areas built over drainage, which combines a route with a food supply.
• Grease interceptors that are not on a service schedule.
• Disused connections from equipment or a previous tenant's layout, capped at one end only.

A blocker on the outgoing pipe does nothing about a missing chamber cover ten metres away, which is the commercial version of the point made everywhere else on this site: closing one route is not the same as closing the routes.

Multiple units

One System, Several Tenants

In a parade, a precinct or a converted building, drainage is usually shared, and a shared run serving more than one property is a sewer rather than a drain — which generally makes it the water company's rather than any tenant's.

The practical consequence is the same as in a terrace of houses, with more money involved. One defect is everybody's problem, each unit treats it separately, and nobody closes the route. Establishing whose pipe it is early is what stops that, and it frequently ends with a free repair rather than five separate invoices.

Where a valve is appropriate it goes in your own branch before the shared run, and attendance can be arranged out of hours so the premises keep trading.

Short answers

Drain Blocker Questions

Going further

Drain and Rat Guides