Signs Your Drain Is Broken or Collapsed

What are the signs of a broken or collapsed drain?

The most common sign is a blockage that keeps coming back, even after the drain has been cleared. A cracked, displaced or partly collapsed pipe catches waste at the damaged point, so the same drain blocks again and again.

Other signs to look out for include:

• Slow drainage across several fittings, such as sinks, baths and toilets all emptying sluggishly at the same time.
• Gurgling noises from plugholes or toilets when water runs elsewhere in the house.
• Persistent sewage smells in the garden, near outside walls or inside, with no obvious blockage.
• Damp patches on internal walls or floors near where the drain runs.
• Sunken or cracked paving, dips in the lawn or a patio that has started to settle.
• Unusually lush patches of grass along the line of the drain, fed by leaking wastewater.
• Rats in the garden, under floors or in the house. Rats can get in and out through broken drains.
• Water standing in an inspection chamber when nothing is running.

One sign on its own isn’t proof of damage. Several together, especially repeated blockages, are a strong reason to get the drain checked.

What is the difference between a broken and a collapsed drain?

A broken drain has damage such as cracks, holes or displaced joints, but still mostly holds its shape. A collapsed drain has lost its shape, either partly or completely, so the pipe is crushed or caved in.

Broken drains often still carry water, just badly, and leak into the surrounding ground. A full collapse can stop the flow entirely, causing backing up into the house, overflowing manholes or flooding in the garden. Cracks left untreated can worsen into a collapse over time as soil washes into the pipe and the ground around it loses support.

Why do drains break in older London homes?

Many London homes, particularly Victorian and Edwardian terraces, still have their original clay drains. Clay is durable, but the pipes are short sections joined together, and those joints are the weak point. Common causes of damage include:

• Age and wear. Joints can crack, shift and separate after a century or more underground.
• Ground movement. Much of London sits on clay soil that swells when wet and shrinks when dry, which can move pipes over time.
• Tree roots. Roots from garden and street trees, including London planes, seek out moisture at cracked joints and can widen them.
• Pitch-fibre pipes. Some homes built or altered in the mid-20th century have pitch-fibre drains, which can deform, blister and flatten with age.
• Heavy loads. Vehicles, skips or building materials over a shallow drain can crack it.
• Building work. Extensions, digging and piling near a drain can disturb or damage it.
• Repeated blockages. Fat and wipes that sit in a pipe can add strain and make damage harder to spot.

How does a CCTV survey confirm a broken drain?

A CCTV drain survey is the most reliable way to find out whether a drain is damaged. An engineer feeds a waterproof camera into the pipe through an inspection chamber or other access point, and the camera sends live video back to a screen above ground.

The footage shows:

• Cracks, fractures and holes in the pipe wall.
• Displaced or open joints.
• Root ingress.
• Deformed or collapsed sections.
• Blockages and build-up, and whether they hide damage behind them.

The engineer can also measure how far along the pipe each defect is, which helps plan the repair and work out whether the damaged section is on your private drain or on a shared pipe. If the drain is badly blocked, it may need to be cleared with high-pressure jetting first so the camera can see the pipe wall.

What does a broken drain repair usually involve?

The right repair depends on what the survey finds: the type of damage, how much of the pipe is affected, its depth and what is built above it. In general terms, the options are:

No-dig repairs such as patching and relining avoid digging up gardens, patios and driveways where they are suitable. A collapse usually needs excavation, because a liner needs an intact pipe shape to work.

Who pays to repair a broken drain?

If the damaged section serves only your home and sits within your boundary, it is usually your responsibility, or your landlord’s if you rent. If it is a shared drain or lies beyond your boundary, it is generally Thames Water’s responsibility since the 2011 private sewer transfer. Some home insurance policies cover accidental damage to drains, so it is worth checking yours.

What should I do if I think my drain is broken?

Don’t ignore it. A small crack can get worse, and leaking wastewater can wash away the soil around the pipe.

1. Note the signs you’ve seen and when they started.
2. Cut down on water use if drains are backing up.
3. Avoid using chemical drain cleaners repeatedly, which won’t fix a broken pipe.
4. Arrange a CCTV drain survey to confirm the cause before agreeing to any repair.

Worried your drain is damaged?

Pipe & Drain Cleaners carries out CCTV drain surveys and drain unblocking across London, including older housing in areas like Ealing and Haringey. We give a fixed quote before any work starts. Call 0800 470 0946 24/7, or book a survey online.

Frequently asked questions