New builds and warranties
Backfill over a service trench on the new plot has settled into a trough. What pipe in that trench was not exposed?
Whatever pipe lies in that trench was not exposed. The survey saw backfill settled into a trough over a service trench on the new plot. A dip shows the fill has sunk. It does not show the pipe, duct or cable the trench was dug for, and the ground was not opened. The note is not a camera survey of a drain and not a test of a main. NHBC describes Buildmark as a 10-year warranty and insurance product. The survey has not opened a claim or uncovered the service.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Service trenches on a new plot carry whatever was laid to the house: water, drainage, electricity, or more than one of those. Backfill that was not compacted can settle into a trough after rain or after the first seasons. The hollow follows the line of the dig. It does not identify which service is underneath, and it does not show a broken joint. The surveyor recorded the trough at the surface. They did not excavate, and a home survey does not test drains or other buried services as standard.
Tell the developer the backfill has settled into a trough, and ask them which service the trench contains. That identification comes from the plot records, not from this report. Ask the solicitor which warranty applies to settling ground on a new plot. NHBC describes Buildmark as a 10-year warranty and insurance product. The survey does not open a claim. Do not open the ground yourself to see the pipe. The service was not exposed, and it stays that way until someone instructed to look does so.
What should you ask your surveyor?
- Where has the backfill settled into a trough?
- Which pipe, if any, was left unexposed?
- Have you recorded surface settlement only, with no drain test?
What are the typical next steps?
- Treat the trough as settled backfill, not as an exposed pipe.
- Ask the developer which service runs in that trench.
- Do not open the ground on the strength of this note.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
If the trough is on the line of a downpipe, is it a rainwater drain?
Not proved. A trough under a downpipe can coincide with a rainwater run, or with any other trench that happens to be there. The survey did not expose the pipe. Settled backfill is all that was seen. Ask the developer what was laid. Do not name the service from the dip alone, and do not treat the note as a drain test.
Does a level lawn elsewhere mean the trench has finished settling?
No. The note is the trough over this trench, not the lawn beside it. Other ground looking level does not refill the hollow, and it does not expose the pipe. The survey has not said settlement is finished. It has not opened a warranty claim. The backfill that has already sunk is the finding.