How-to
Rats in Your Drains: What It Means, How They Got In, and How to Shut the Door
A rat in the garden, or worse, the toilet, usually means a broken drain. Here's how rats use damaged pipes, and how a survey finds the way in.
Published 15 August 2026
Let’s get the uncomfortable truth out of the way first: there are rats in the sewers under every street in the country, including the nice ones. That is where urban rats live. It is normal, it is invisible, and it is not your problem.
It becomes your problem at exactly one moment: when the pipework between your house and that sewer stops being sealed. A rat in your garden with no obvious food source, scratching under the floorboards, or making its entrance up the toilet is not a lifestyle choice. It is a building inspector with a tail, reporting a fault in your drains.
How they actually get in
Rats follow warmth, food smells and air movement, and a defect in a drain leaks all three. The classic routes, in the order we find them:
- A broken or displaced joint. Twickenham’s Victorian terraces run on original clay pipes with a joint every 600mm, and a century of tree roots and ground movement has opened plenty of them. A gap a few centimetres wide is a rat-sized door.
- A redundant pipe. An old outside toilet removed in the seventies, a demolished extension, a capped-off run that was never actually capped. The drain map of an old house is an archaeology site, and rats are enthusiastic archaeologists.
- The soil pipe itself. A rat that gets into your private run can climb the vertical soil pipe, which is how you get the toilet scenario. They are, regrettably, excellent swimmers. We are sorry to be the ones to tell you.
Why pest control alone doesn’t end it
Bait and traps remove the current rats. They do nothing about the doorway, so the sewer sends replacements, and you are now in a subscription relationship with a problem that has a one-off fix.
The one-off fix is finding the breach. A CCTV survey puts a camera through the whole run and shows the entry point on screen: £150 to £350 depending on the length of drain, price agreed first. Then it is usually one of two jobs:
- Seal the defect. A patch repair cures a sleeve over the break from inside the pipe, no excavation, £300 to £600. Broken joint closed, doorway gone.
- Fit a one-way flap where the route in is the pipe run itself. Waste and water flow out; nothing walks back up. Simple, mechanical, and deeply satisfying to install.
Worth knowing: a defect big enough to admit a rat is also leaking waste water into the ground, which is how you eventually get the sunken lawn and the re-blocking drain. The rat is annoying, but it may have done you a favour by reporting the crack early, while it is a £300 patch rather than an excavation.
What to do today
If it is the toilet scenario: lid down, weight on top, call. Otherwise, note where you are seeing them, do not block any holes yet (sealing a rat in is a smell you only make once), and get the camera down the run. Find the door, shut the door. The sewer can keep its residents; your drains just need to stop offering them a spare room.