Who is responsible for repairing my drain, me or the water company?

On 1 October 2011 most private sewers and lateral drains in England and Wales transferred to the local sewerage undertaker. Across every area we cover, that undertaker is Thames Water. In practice: the pipework inside your boundary that serves only your property is yours. The lateral drain, meaning the length that continues past your boundary to the public sewer, is normally Thames Water’s. A drain shared with other properties is usually theirs too, even where it runs under your garden. Pipework laid after the transfer date, or serving only your building, stays private. A CCTV survey that fixes the defect’s position relative to your boundary is what settles the question, and it is worth settling before you agree to pay.

The blockage was cleared and it came straight back. Why?

Because clearing removes what collected, not the reason it collected. A displaced joint, a fracture, a dropped section or root ingress will catch material again within weeks. If a drain has blocked more than once in the same place, the useful next step is a survey rather than another clearance.

Do I really need a CCTV survey before a repair?

For any structural repair, yes. The choice between a patch liner, a full-length liner and an excavation depends entirely on what the defect is, where it is and how far it runs. Nobody can specify that without looking. A quote for a drain repair given without a survey is a guess, and the risk of that guess sits with you.

What is the difference between drain repair, resealing and lining?

Repair is the general term for fixing structural damage to the pipe. Resealing addresses the joints specifically, which on older clay drainage is usually where failure starts: the joints open, roots get in, and groundwater and soil move through them. Lining, more precisely cured-in-place lining, installs a resin liner inside the existing pipe that hardens into a continuous jointless pipe. A patch liner does the same over a short section rather than the whole run.

Will you have to dig up my driveway or garden?

Often not. Where the pipe still has a bore to work through, it can be repaired from the inside via an existing access point and nothing above ground is disturbed. Excavation becomes necessary when the pipe has collapsed, is badly deformed, or is already too small to take a liner. The survey tells us which case you are in before anything is agreed.

Does lining make the pipe narrower?

Slightly, yes. A cured-in-place liner reduces the internal diameter by a few millimetres. On a standard 100mm or 150mm drain in reasonable condition that is not a problem. On a pipe that is already undersized, badly deformed or heavily scaled, it can be, and in those cases lining is the wrong answer. We will say so rather than line something that should be replaced.

There is no blockage, but I have a drain smell and damp. Is that a drainage fault?

It can be, and a leaking drain is the most commonly missed cause. A cracked pipe below ground can leak continuously without ever blocking. The signs are damp at the base of a wall, a persistent smell in a garden or downstairs room, ground that stays soft in dry weather, and paths or patios that sink. A dye test alongside CCTV is what proves whether the drainage is the source.

My drain runs full of water even when nothing is being used. What causes that?

Usually groundwater infiltration rather than foul flow. Where the water table sits above the pipe, every crack and open joint is an inlet and the drain runs continuously. It is common on the Thames floodplain areas we cover, through Staines, Chertsey, Datchet, Windsor and the Colne valley, and in the chalk valleys of Hertfordshire and the Chilterns after a wet winter. Sealing the defects stops it, and it is worth doing because that same infiltration is what surcharges the system in heavy rain.

Roots keep getting into my drain. Can that be stopped for good?

Cutting roots out clears the pipe but does not stop them returning, because they are entering through a defect. Sealing the way in, with a patch over the specific joint or a liner along the run, is what makes it permanent. Once there is no opening, there is nothing for the roots to grow towards, and the tree does not need to be removed.

What do I get at the end of the job?

The CCTV footage and a written report, before and after. The defects are located by distance from the access point and coded against the standard drain condition classification, so what you are given is the same thing an independent surveyor, an insurer or a buyer’s solicitor would record. The footage is yours to take elsewhere for a second opinion if you want one.

Can I claim a drain repair on my buildings insurance?

Sometimes. Policies vary a great deal, and cover for underground services is often an optional extension rather than standard. Damage caused by a sudden collapse is treated differently from gradual deterioration, which most policies exclude. What helps either way is documentary evidence: dated CCTV footage and a coded condition report. Check your own policy wording, and ask your insurer before work starts rather than after.

I am buying a property and the survey mentioned drainage. What should I do?

Get a drainage CCTV survey done before you exchange. A homebuyer’s survey does not include the buried drainage, and the standard conveyancing enquiries will not tell you the condition of the pipework. A survey gives you the condition, the location of any defect, and whether it sits on your side of the boundary or Thames Water’s, which is the difference between a cost you inherit and one you do not.

Still stuck?

Call 07438 912191 and describe what you are seeing. If it is a drainage fault we will tell you what the next step is, and if it is not, we will tell you that too.

Drain repair · Drain resealing · Leaking drain repair · Areas we cover

Drainage Questions We Get Asked