A pre-purchase drain survey costs little against what it can uncover, because in London's Victorian housing, surveys can find roots, collapsed sections and slipped joints. A standard homebuyer report will not show any of these. A defect found after exchange can cost thousands to repair, so the survey can pay for itself the first time it finds anything.
This checklist covers what a London buyer needs to know before booking. While you read, note that it also explains what to expect on the day, and how to use the findings before exchange.
Who Should Book a Pre-Purchase Drain Survey
Any buyer of an older property. Victorian and Edwardian drains in London are mostly clay laterals, about 100mm wide. They run under gardens and back additions before they reach the public sewer. Since they are over a century old, these pipes develop roots, crack under London Clay movement and gather grease. Problems are common, not rare.
Buyers of converted flats. Converted houses usually share soil and waste stacks and a single combined lateral. A defect in the shared run affects every flat at once, so while it is shared, you need to know the layout and condition before you buy, especially if the lease says little about drain maintenance.
Anyone buying fast or above the asking price. Because speed leaves less time to check, if you are waiving survey conditions to secure the home, a drain survey is one of the quickest and cheapest ways to rule out hidden costs.
Buyers whose building survey raised drain concerns. A note such as "drains not inspected" or "recommend drainage investigation" in a RICS report is a prompt to act, yet it is not a reason to accept doubt.
The Pre-Purchase Drain Survey Checklist
Before you book
Because the details matter, check these points first.
- Confirm the survey covers every accessible drain run, such as the kitchen drain, the bathroom stack, external gullies and the combined lateral to the boundary
- Ask whether the report uses a recognised defect-coding standard, because most lenders and solicitors expect one
- Confirm you get full digital footage with the written report
- Check whether the price includes a camera pass after jetting, since a clean pipe gives more reliable results on older drains
- Ask whether the firm will re-survey if defects are repaired before exchange
While prices vary, see our pricing guidance on the CCTV drain survey cost page.
On the day
Since the day is short, here is what happens on site.
- The engineer needs access to the property and all external inspection chambers
- A simple survey is quick, although a complex home with many runs or no chambers takes longer
- The engineer runs the camera through each run, records footage and notes where each defect is, what type it is and how severe
- You should get a verbal debrief on the day that covers any major findings
Reading the report
Because the report is coded, it lists each defect with these details.
- A defect code for the type, such as root intrusion, displaced joint or fracture
- A grade from minor, which you can monitor, to severe, which needs action
- A photograph and the distance from the camera entry point
- A recommended action, such as monitor, jet, reline or excavate
The most severe grades shape your negotiating position. Minor defects on a Victorian property are common, yet they are rarely a reason to renegotiate unless there are many.
Using the findings before exchange
Renegotiate on the purchase price. A severe root intrusion that needs excavation is a fair reason to lower your offer. As a result, you should get a repair quote and use that figure as your basis.
Ask the seller to repair before exchange. For serious defects, a repair plus a camera check afterwards is cleaner than a price cut. Because it removes doubt, you know what you are buying.
Walk away if the drainage is beyond economic repair. Occasionally a survey shows collapse or root damage along the whole lateral. While rare, if access is tight, such as a rear flat or a basement conversion, repair costs can be very high. The survey saves you from buying that liability.
What a Pre-Purchase Survey Does Not Cover
A CCTV drain survey checks accessible drain runs inside the boundary, down to the first reachable junction with the public sewer. However, it does not do the following.
- Survey Thames Water's adopted public sewers, which are Thames Water's responsibility following the 2011 private sewer transfer
- Inspect runs with no accessible entry point, since a run you cannot reach from a chamber, gully or toilet cannot be filmed
- Confirm the condition of the soil and waste stack above ground, because a building survey covers that
Since some runs have no chambers, if the property has them, ask the firm whether it can fit temporary access points or work from a ground-floor toilet.
What the Survey Costs Depends On
Because the scope varies, the price follows the scope of the job.
- A standard survey of a single-run home is the simplest and cheapest option
- A survey with several runs or tricky access costs more, because it covers more
- A combined jet and survey, which we recommend for older homes, is an add-on to the survey price
- A re-survey after the seller's repairs is priced separately from the first one
Inner London homes with restricted access, such as basement flats, tend to cost more, since the work is harder. See our full pricing page for guidance.
Since our CCTV drain survey service covers all 32 London boroughs, help is close. It includes coded reports and full digital footage.
Frequently Asked Questions
Can I book a drain survey before making an offer?
Yes. You do not have to wait until an offer is accepted. Some buyers survey before they bid on a home they really want, especially at auction, since there is no cooling-off period. Request a quote online to check availability.
Does the vendor need to be present during the survey?
No, but they must give access, since it is their home. The estate agent usually arranges this. The survey causes no disturbance to the property.
Will my solicitor accept the survey report?
Most solicitors accept a coded report from a competent drainage firm. However, if your solicitor has set requirements, confirm the format with them before you book.
What happens if the survey finds major defects?
You have three options. You can renegotiate the price, ask the seller to repair before exchange, or withdraw. While you decide, we can provide repair quotes with the survey report to support any of these.
How long is a pre-purchase survey report valid for?
Lenders and solicitors differ on how long they treat a report as current. Since your purchase may drag, if it takes takes a long time, a re-survey may be needed. Request a quote online via our contact form for advice on your own case.
Because every property is different, start with our guides to cctv drain surveys and bathroom drain blockages advice. We also cover cctv drain surveys in Camden and cctv drain surveys in Canary Wharf, so you can see how the work runs near you.
