Electrics and gas
Does water sitting in an oil-tank catchpit mean the tank is leaking?
Not by itself. A catchpit or bund is there to hold a spill, and rain fills an uncovered tray as well. A surveyor who sees water has not emptied it, dipped the tank or tested the boiler. Staining that smells of oil, or a pipe that is dripping oil, is a different observation from rainwater. A home survey does not certify the installation. Approved Document J is England’s guidance on fuel storage when building work is done. It is not a pass awarded on the day of the inspection.
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 tray full of rain hides the base. The useful comment is what the surveyor could actually see: water only, an oil smell, a rotten stand, a tank on bare soil, or a fire valve they could not reach. None of those notes is a combustion test, and none of them is a measured clearance taken from Approved Document J. Do not invent a distance from a photograph. A dry tray is not a guarantee either. Plastic tanks age and stands fail without leaving a puddle on the day of the visit.
If oil is reaching a drain or the ground, stop using the tank and ask someone competent for oil appliances to look. A Gas Safe registration is for gas work, which is what HSE’s domestic gas guidance is about. It does not automatically cover an oil boiler. GOV.UK’s competent-person schemes are about notifying certain building work, not a service record for last winter. Wales has its own building regulations, so do not treat the English document as a Welsh approval. There is no RICS price for emptying a catchpit or replacing a tank.
What should you ask your surveyor?
- Did you see oil, or only water in the catchpit?
- Could you see the base, the stand and the fire valve?
- Are you limiting this to a visual note, not a service?
What are the typical next steps?
- Do not empty a catchpit of unknown liquid yourself.
- Ask an oil-competent technician if there is staining, a smell, or a base you cannot trust.
- Name the fuel as oil when you ask the seller for a service record, so nobody prices a gas-only visit.
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 plastic oil tank a defect because it is plastic?
No. The material is common. Leaks, a failed base, a tray that hides the underside, and a tank the surveyor could not get near are the comments. Age alone is not a rating.
Does rain in the tray prove the tank meets fuel-storage guidance?
No. Approved Document J applies when building work is done in England. A wet tray is not that check, and a dry tray is not one either.