Electrics and gas
An empty glycol top-up bottle stands by the ground-source manifold. Has the brine strength been measured?
No. The brine strength has not been measured. An empty glycol top-up bottle by the ground-source manifold shows a container, not a test. Glycol is added to the ground loop so the brine is protected in cold weather. An empty bottle can mean it was used, that it is leftover, or that it is unrelated. The survey did not sample the loop and did not decide the mixture is weak or strong. The visit recorded the bottle. The brine stays untested.
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?
The manifold is where the ground-loop circuits are gathered. Strength of the brine is a property of the liquid inside those pipes, read with proper test equipment on a sample. Looking at an empty bottle beside the manifold does not open a pipe and does not read a result. The survey must not invent a concentration. Top-up habits, leaks and a bottle left from installation are all still possible. None was separated on this visit.
Ask a ground-source engineer if you need the brine sampled and the manifold checked. Tell your solicitor the bottle was empty and that no strength result exists in the survey. The survey does not decide grant eligibility. Do not tell a lender the loop is protected, or that it has lost its glycol, because the bottle was empty. The container is a clue without a measurement. Leave the strength unknown.
What should you ask your surveyor?
- Was the empty bottle recorded without a brine sample?
- Did the visit avoid measuring strength at the manifold?
- Is any service record for the ground loop outside this report?
What are the typical next steps?
- Treat brine strength as unmeasured.
- Ask an engineer if the loop needs a proper sample.
- Do not read the empty bottle as a failed or a healthy mixture.
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
Could the bottle have been emptied at installation and left there?
Yes. An empty bottle can be rubbish from commissioning, a later top-up, or something else entirely. The survey did not date it and did not sample the brine. Each of those histories is possible. None is proved by the bottle standing at the manifold. Strength inside the pipes remains unmeasured.
Does a pressure gauge on the manifold measure glycol strength?
No. A gauge, if one was visible, reads pressure, not the strength of the brine. The survey did not treat any gauge as a chemical test and did not take a sample. Pressure and mixture are different facts. The empty bottle does not turn a gauge into a strength result.