Drain Survey Findings When Buying a House: What They Mean and Cost

Surveyors can lift a manhole cover and run a tap, but they can't see inside the pipes. So on older houses, or where there are trees near the drains, they'll often recommend a CCTV drain survey. It's one of the best-value checks you can do before exchange: it costs £200–£400 and the report usually comes with a price for any repair.

The harder part is reading it. Here's what the common findings mean.

The common findings

Root ingress. Tree or shrub roots have got into the pipe through a joint or crack. Minor roots can be cut out with a jetting machine. Heavy roots usually mean the joint has opened, and it needs a liner or a repair afterwards, or the roots come back.

Displaced or open joints. Sections of pipe have moved apart or out of line. Small displacements are common in old clay drains and often left alone. Large ones catch debris, let water out into the ground and let roots in.

Cracks and fractures. A longitudinal crack along the pipe or a circumferential one round it. Usually repairable from inside with a patch liner.

Deformation. The pipe has squashed out of round. This is typical of pitch fibre pipes, used in some houses built roughly from the 1950s to the 1970s, which soften and flatten with age.

Collapse. Part of the pipe has broken and fallen in. This needs digging up and replacing, and it's the one to take seriously, because a leaking drain can wash out the ground under a foundation and cause movement.

Ponding or a back-fall. Water sits in a dip instead of running away. Minor ponding is common. A serious back-fall causes repeated blockages.

Most reports grade each defect. Concentrate on anything graded severe, and anything near the house or under an extension.

Who is responsible for which pipe

This matters, because some of what the camera finds may not be yours to fix. In England and Wales, since 1 October 2011:

• A drain that serves only your house, within your boundary, is yours.
• A pipe shared with neighbours, or the part of your drain outside your boundary (the lateral drain), is normally the responsibility of the local water company, if it was connected to the public sewer before July 2011.

So a collapse in a shared run at the back of a terrace may be a call to the water company, not a bill for you. Scotland and Northern Ireland have different arrangements, so ask your conveyancer there.

Your conveyancer's drainage search will also show any public sewer running under or near the house. If a previous owner built an extension over one without the water company's agreement, that's a question for your conveyancer before exchange.

What the repairs cost

My rough 2026 figures:

• CCTV drain survey: £200–£400
• High-pressure jetting to clear a blockage: £100–£300
• Root cutting: £150–£500
• Patch liner for a single crack or joint: £300–£900 per patch
• Relining a full run: £1,000–£3,000
• Excavating and replacing a collapsed section: £1,200–£5,000, more under a patio, a drive or an extension

The negotiate figure I use for "drain collapse or root ingress" on a survey is £1,200 to £8,000. The drain report narrows that down, which is exactly why it's worth having before you renegotiate.

Using it before exchange

1. Ask the drainage firm for a written price for any repair they recommend, with the defect location.
2. Check responsibility for anything on a shared or lateral drain.
3. Prioritise collapses and anything near the foundations. Minor roots and small displaced joints are maintenance.
4. Add the costed items to your list for the seller. See how much you can negotiate off after a survey.

If there's cracking near a leaking drain, see subsidence, settlement or thermal movement. For the other specialist checks, see what each "further investigation" costs.