Oil tank inspection

When an inspection is worth having

• Before buying a property with oil heating. A standard homebuyer survey will note that there is a tank. It will not tell you whether it complies, whether the base is sound, or whether it is two years from needing replacement. This is a genuinely useful thing to know before exchange.
• When the tank passes fifteen years. That is the point at which planning a replacement becomes sensible and reacting to one becomes likely.
• After a hard winter, particularly for plastic tanks, where frost heave on a marginal base does real damage.
• When an insurer or lender asks. Some policies now ask specific questions about oil storage, and a written report answers them.
• Before a property is let. There is no statutory oil equivalent of a gas safety certificate, but a landlord with a failing unbunded tank near a ditch has a liability whether or not a regulation names it.
• If you have inherited a tank with no history, which describes a large proportion of rural Norfolk.

What we look at

The tank

Material and construction, age where it can be established, and condition. On plastic: crazing, discolouration, bulging, deformation, seam condition and any weeping. On steel: external corrosion, the condition of seams and welds, evidence of internal rusting, and the state of any protective coating. On both: whether the tank is sitting level and whether it is bearing correctly on its supports.

Secondary containment

Whether the installation requires bunding under a current risk assessment, whether it has any, and if so whether the bund is intact and functional. An integrally bunded tank with a cracked outer skin or a bund full of rainwater is not providing containment, and a bund that has never been emptied is a common find.

The base and supports

Level, condition, extent, material and load bearing. Whether the base extends far enough beyond the tank. Whether water is draining away from the tank or pooling under it. Whether any subsidence or heave has occurred. This is the single most common underlying cause of tank failure and the easiest thing to overlook.

Siting and separation

Distances to the building, openings, eaves, boundaries, flue terminals and combustible screening, measured rather than estimated, and assessed against the requirements in Approved Document J. Where distances are not met, whether adequate fire protection exists.

Environmental risk

Proximity to watercourses, ditches, drains, gullies, soakaways and any water supply source. This is what determines whether containment is required, and in Norfolk it is very often the deciding factor.

Fittings and the oil line

Fill point, cap and security, vent and vent outlet visibility, contents gauge accuracy, outlet valve operation, filter condition, and the supply line from tank to appliance including its material, protection, joints, any flexible sections, and the presence and correct siting of a remote-sensing fire valve.

What you get

A written report setting out what was found, what is non-compliant, what is a defect, and what is simply worth keeping an eye on. Photographs of anything significant. Where remedial work is needed, a clear statement of what it is and how urgent it is – separated into things that need doing now, things that need doing this year, and things to plan for.

What you will not get is a report engineered to produce a quote. We do this work because it is genuinely useful to know, and a report that says the tank is fine for another eight years is a perfectly good outcome.

What tends to turn up

Across the tanks we look at, the recurring findings are fairly consistent, and almost all of them are cheaper to fix than to ignore:

• Bases that have settled, cracked or were only ever paving slabs on sand.
• Bunds with a season’s rainwater sitting in them, which both reduces containment capacity and accelerates corrosion on steel tanks.
• Sight gauges perished to the point of being one knock away from emptying the tank.
• Vent caps missing, letting rain straight into the tank – the origin of most water-in-fuel problems.
• Fire valve sensors that have fallen out of position, or were never correctly sited, meaning the valve would not do its job in a fire.
• Oil lines run above ground in plastic across a driveway, or buried without protection.
• Combustible fencing or a shed built up against a tank since it was installed, destroying separation distances that were compliant when it went in.

That last one is worth emphasising. A tank installation that was correct in 2006 can be non-compliant in 2026 without anybody touching the tank, simply because a fence or an extension arrived. Nobody reassesses it because nothing visibly changed.