Damp and moisture meters
Is a dripping overflow that keeps wetting one patch of brick actually rising damp?
No. A dripping overflow wetting one patch of brick is a discharge from a cistern, a tank or a WC fitting. It can green the brick and damage that patch. It is not water rising evenly from the ground, and it is not proof the damp-proof course has failed.
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?
Overflows are supposed to run only when a valve has failed or a tank is overfilled. A pipe that drips all day soaks one vertical patch, often with algae and spalled faces, and the inside face behind that patch can stain. The rest of the wall at floor level can be dry. Rising damp is not a single drip-shaped patch under a pipe. A surveyor can see the pipe and the stain. They do not service the ballvalve.
The repair is to stop the discharge and then to see whether the masonry dries. A RICS home survey records the visible plumbing and the damp it is causing. It does not pressure-test the cistern and it does not guarantee pipes that are boxed in. Replacing the damp-proof course would leave the drip in place. Ask which fitting the pipe serves before you treat the wall as a ground-moisture problem.
What should you ask your surveyor?
- Which fitting does the dripping pipe appear to serve?
- Is the staining limited to the patch under the outlet?
- Are you describing a plumbing discharge, or the damp-proof course?
What are the typical next steps?
- Photograph the drip and the brick stain together.
- Do not inject the wall while the overflow is still running.
- Ask a plumber about the valve or the tank. The survey did not repair it.
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
Is a dry overflow on survey day a pass?
No. A pipe that is dry that morning may still run when the tank fills. The stain on the brick is the longer record.
Can the same pipe wet the inside face?
Yes, if it has soaked the wall for long enough. The shape should still match the pipe, not a tide along the floor.