Electrics and gas
The loft header tank is overflowing onto the insulation. What overflow pipe was not traced, and what drinking-water sample was not taken?
The overflow pipe from the header tank was not traced, and no drinking-water sample was taken. The tank is overflowing onto the loft insulation, so water is leaving the cistern and wetting the quilt instead of running to a visible outlet. The survey has recorded the spill and the wet insulation. It has not followed the overflow pipe to a terminal, has not found whether that pipe is missing, blocked or disconnected, and has not sampled the water. Wet insulation is a damp finding in the loft. It is not a test of whether the water is fit to drink.
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?
A header tank holds water for stored supply or for the heating, and its overflow should discharge where a failed valve can be noticed. If the pipe is missing or does not reach outside, the water spills onto the insulation. The survey saw that spill. It did not trace the pipe through the roof space to an outlet, so the pipe itself is untraced. Wet quilt can soak a ceiling below. That is the building defect in view. It says nothing about what is dissolved in the water.
Tell the solicitor the loft tank is overflowing onto the insulation and that the overflow pipe was not traced. Ask a plumber to find the pipe and to deal with the cause, as a separate instruction. Do not treat the tank as drinking water on the strength of this report, and do not expect a sample the survey never took. The note is an overflow wetting the loft. It is not a water-quality result.
What should you ask your surveyor?
- Where is the header tank overflowing onto the insulation?
- Was the overflow pipe left untraced?
- Was any drinking-water sample left untaken?
What are the typical next steps?
- Treat the overflow pipe as untraced.
- Ask a plumber to find the pipe and the cause of the overflow.
- Do not read wet insulation as a drinking-water result.
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 ceiling below is dry, has the overflow stopped mattering?
A dry ceiling does not trace the overflow pipe and does not sample the water. The tank was overflowing onto the insulation, which is the finding. The ceiling may simply not have stained yet. The survey has not called the loft satisfactory and has not tested the water. The pipe remains untraced.
Is the header tank the same thing as the drinking supply to the taps?
The survey has not said so, and it took no drinking-water sample. Some loft tanks feed heating circuits only, and some older stores feed taps. This visit did not map that pipework and did not test the water. The overflow onto the insulation is the damp note. What the tank supplies was not established.