Homebuyer drain survey: know what's under the garden before you exchange

Why your house survey won't tell you about the drains

Your mortgage valuation isn't a survey at all. It's for the lender, to check the house is worth the loan.

A RICS Home Survey Level 2 (what used to be called the HomeBuyer Report) goes further, but it's still a visual inspection. RICS's own description says the surveyor may lift accessible inspection chamber covers and look inside where it's safe to. It also says drainage isn't tested and the drainage installation isn't investigated. A Level 3 building survey is more thorough, but it doesn't put a camera down the pipes either.

So the part that actually fails, the pipe between the chambers, is the part nobody sees. If your surveyor spots a warning sign, the report will usually suggest a specialist drain survey.

Your conveyancer's drainage and water search (the CON29DW) answers different questions: whether the house connects to the public sewer, whether a public sewer is shown inside the boundary, and whether building near one was approved. It says nothing about the pipes' condition.

Which homes most need a pre purchase drain survey

Any house can have a broken drain, but these are the ones we'd never skip.

Older houses

Victorian, Edwardian and interwar homes mostly have clay drains with rigid joints. A century of ground movement opens those joints and cracks the pipes.

Homes with trees nearby

Roots find the smallest gap. A mature tree or big hedge near the drain run is a classic cause of cracked pipes, and the damage is invisible from the garden.

Houses built from the 1950s to the 1970s

Many homes of this era were laid with pitch fibre drains, made from wood fibre soaked in tar pitch. They were light and cheap to lay, but with age they soften, blister inside and sag out of round. A pitch fibre drain in poor condition usually needs relining, and the survey tells you how much of it.

Extensions and conservatories

If a previous owner built over or near a drain, check two things: that the pipe underneath is still sound, and, if it's a public sewer, that the water company agreed to the work. The survey answers the first. Your conveyancer's search helps with the second.

Shared drains

Terraced and semi-detached houses often share a drain run. Since October 2011, most pipes serving two or more homes have been public sewers, which the water company maintains. That's good news for repair bills, but it matters if you plan to extend, because building over or close to a public sewer needs the water company's consent. Our guide to who is responsible for blocked drains explains where your pipe ends and theirs begins.

When to book a drain survey before buying a house

Book it as soon as your offer is accepted, alongside your building survey, and well before exchange of contracts. Until you exchange, you can renegotiate or pull out. Once you've exchanged, you're legally committed, and any drain problem comes with the house.

Getting the seller's permission

The drains belong to the seller until completion, so we need their agreement. Ask the estate agent to arrange it, and mention that we'll lift the manhole covers and run the taps and toilets. If covers are painted shut or hidden under decking or gravel, ask the seller to uncover them, or warn us so we come prepared.

What the homebuyer CCTV drain survey report tells you

The report is written for someone making a decision. It opens with the questions you actually have: are the drains sound, what's wrong if not, how urgent it is, and what kind of work would put it right. Behind that sits the detail: a plan of the runs, each defect graded and located, stills and the footage. For how defects are coded and graded, see our CCTV drain survey page.

Using the survey to renegotiate the price

If the camera turns up a problem, you have choices, and you have them before exchange.

• Ask for a price reduction that covers the repair. A fixed repair quote carries more weight than a rough guess, so ask us to price the work.
• Ask the seller to repair it before completion, with proof the work is done, such as follow-up footage.
• Agree a retention, where part of the price is held back until repairs are finished. Your conveyancer will check whether your lender allows it.
• Walk away, if the repair is more than the house is worth to you.
• Check who is responsible first. If the fault is in a shared pipe that's now a public sewer, the water company fixes it, not you or the seller.

For scale: a single patch repair starts from £250, and drain relining is typically £80 to £150 per metre. A collapsed drain repair that needs digging costs more.

Homebuyer drain survey cost

What a homebuyer drain survey can and can't tell you

• It can: show the condition of every run the camera reaches, locate each defect, and show which pipes are shared and where they run near an extension.
• It can't: promise the drains will stay sound after you move in. It covers what the camera can reach, and any run without an access point is named in the report.
• It doesn't cover: off-mains systems such as septic tanks and treatment plants, which need their own inspection, or the clean water supply pipe.
• It isn't a legal search: whether an extension had the water company's consent is for your conveyancer to confirm.

Recent homebuyer surveys

A few of the pre-purchase surveys we've done lately, and what buyers did next.

What we promise on every homebuyer survey

Your report arrives within 48 hours of the survey. If you buy the house and we carry out a repair the survey found, that work comes with our 10-year guarantee on relining and repairs. The details are on our guarantee page.

Areas we cover for homebuyer surveys

Buying in Dorset or Hampshire? Our engineers are based in Bournemouth, Poole and Christchurch and survey homes for buyers across Dorset and Hampshire.

Homebuyer drain survey FAQs

Buying a house with older drains?