Rats in Drains: How They Get In, Rat Blockers and Who Is Responsible

Rats in drains usually come from the sewer network and escape through cracked pipes, displaced joints and disused connections into walls, floors and gardens. A camera survey finds the entry point, repairs seal it, and a rat blocker (a one-way valve) stops rats travelling back up the pipe. Our rats in drains service does all three, from £189 + VAT, across Nottingham and the East Midlands.

This guide explains how rats use defective drains, how rat blockers work, what the council's pest control team does, and who is responsible for the drain, the sewer and the rats.

Do rats really live in drains?

Yes. Brown rats live in sewers and move through pipework that is damaged or badly connected. In an article published by the British Pest Control Association (BPCA), a member pest controller estimates that on average 80% of rat infestations in the home originate from drainage, whether from a defective drain, a dry line not capped off correctly when an extension was built, or drainage altered to add extra utilities.

That is why rats that come back after bait or traps usually point to the drains. Pest control removes the rats already inside; drainage work stops new ones arriving.

How do rats get out of drains and into homes?

Rats get out wherever the drain is no longer a sealed pipe. The common routes are:

• cracked or broken pipes, especially old clay pipes;
• open or displaced joints, where lengths of pipe have moved apart;
• disused connections left open after a kitchen, bathroom or extension was altered;
• missing interceptor stoppers or broken benching in inspection chambers;
• damaged gully grids and chamber covers at ground level;
• boxed-in soil pipes where a defect near the base gives a route into the walls.

Once out of the pipe, a rat can reach the soil around the house, voids under suspended floors, wall cavities and lofts. Approved Document H (paragraph B.17) says disused drains or sewers "provide ideal nesting sites for rats", and that they should be disconnected near the point of connection. It says shallow disused pipes under 1.5 m in open ground should be removed where practicable, and others sealed at both ends and grout filled.

What are the signs of rats in drains?

• Scratching or scurrying in walls, ceilings, under floors or around boxed-in pipes.
• Droppings, grease marks or gnawing near pipes, kitchen units or airbricks.
• Burrows beside drains, inspection chambers or patios.
• A stale smell that doesn't go away.
• Drains that keep blocking or smelling (see our guide to why drains smell).
• Rats returning after pest control treatment.

The last one matters most. If treatment clears the rats but they keep coming back, the way in hasn't been found.

How do you find where rats are getting in?

A drain investigation looks for the route, not the rats. It usually combines:

1. A CCTV survey, where a camera travels through the pipes looking for cracks, open joints and redundant connections.
2. Smoke or dye testing, to show where drains leak or connect to places they shouldn't.
3. Chamber checks, lifting covers to look for missing stoppers, broken benching and signs of rat movement.

The survey also shows whether each defect is in your private drain or a shared pipe, which decides who pays. Our guide to CCTV drain survey reports explains what the findings mean.

How do rat blockers work?

A rat blocker is a non-return valve fitted inside the drain, usually at the outlet of an inspection chamber. A hinged flap swings open to let waste flow out towards the sewer, then closes again, so rats coming up from the sewer meet a closed flap.

Approved Document H (paragraph 2.22) recognises the approach. It lists rodent control measures including sealed drainage, intercepting traps with locking stoppers, rodent barriers such as "one way valves in underground drainage", metal cages on vent stack terminals, and gully covers or gratings that can be fixed in place.

A rat blocker works best as part of a wider fix:

• repair cracks and open joints with patch repairs or drain relining;
• cap or remove disused pipes, as Approved Document H recommends;
• replace missing stoppers, broken gully grids and damaged chamber covers;
• fit the valve where it can be reached for checking and cleaning.

A rat blocker on a pipe that still has a crack further up does little, because the rats simply use the crack.

Who is responsible for rats in drains?

It depends on what you are asking about: the pipe, the sewer, or the rats. This table sets it out.

The pipe rules come from the 2011 transfer of private sewers. Citizens Advice explains that you are responsible for drains within your boundary that serve only your property, and that the water company is responsible for shared sewers and lateral drains. Across Nottinghamshire and most of Derbyshire and Leicestershire that is Severn Trent; across most of Lincolnshire it is Anglian Water. Our guide to who is responsible for blocked drains explains the split in more detail.

What is the council's role with rats?

Councils have a legal duty over rats in their area. Section 2 of the Prevention of Damage by Pests Act 1949 says it is the duty of every local authority to take such steps as may be necessary to secure, so far as practicable, that their district is kept free from rats and mice, including carrying out inspections and enforcing the duties of owners and occupiers.

Under section 4 of the same Act, the council can serve a notice on the owner or occupier of land requiring reasonable steps to keep it free from rats, and that notice can require "structural repairs or other works". In practice, that can include putting a defective drain right.

Many councils also offer paid pest treatments. Nottingham City Council lists domestic rat treatments at £115 inside and £100 outside, free for residents receiving Council Tax Support (prices as listed on 1 October 2026). Other councils in Nottinghamshire, Derbyshire, Leicestershire and Lincolnshire set their own services and charges.

How can you make your home less attractive to rats?

Drainage repairs close the route; good housekeeping removes the reasons rats come looking:

• keep food waste in sealed bins and don't leave bags out overnight;
• clear spilled bird seed, and don't overfill feeders;
• keep gully grids and chamber covers in place and in good repair;
• don't pour fat or food scraps down sinks, which feeds rats in the pipes (see our guide to fat, oil and grease);
• ask builders to cap off any pipe they disconnect during an extension or refit.

Rats can carry disease. Wear gloves, never handle droppings with bare hands, keep children and pets away from bait, and don't lift heavy or stuck covers yourself.

When to call a professional

Call a drainage engineer if rats keep coming back after treatment, you can hear them near pipes, or you've found burrows beside a drain or chamber. Another round of bait won't fix a broken pipe.

Our rats in drains service starts from £189 + VAT. We survey the drains with CCTV and smoke or dye testing, repair the entry points, cap disused connections and fit rat blockers, and we're happy to work alongside your pest controller. A CCTV drain survey on its own starts from £149 + VAT. Repairs such as lining and patching carry a 12-month guarantee, there is no call-out fee, and the price is agreed before work starts.

We work 7 days a week, 6am to 8pm, across Nottingham, Nottinghamshire, Derbyshire, Leicestershire and Lincolnshire. Book online or call 07300 600 950.

Sources

• BPCA: drainage inspections for rodents
• Approved Document H: Drainage and waste disposal (gov.uk)
• Prevention of Damage by Pests Act 1949, section 2 (legislation.gov.uk)
• Prevention of Damage by Pests Act 1949, section 4 (legislation.gov.uk)
• Nottingham City Council: pest control
• Citizens Advice: who is responsible for repairing drains and sewers