Most oil tanks reach the end of their life somewhere between fifteen and twenty-five years, and a replacement is the point at which the installation has to be brought up to current regulations – which often means bunding and a different position from the old one. The old tank has to be drained, cleaned and disposed of properly.
Why a replacement is not a like-for-like swap
The single most common misunderstanding about tank replacement is that the new tank simply goes where the old one was. Frequently it cannot. Tanks installed in the 1990s and early 2000s were put in under different expectations, and a great many of them would not be permitted in the same position today – too close to a building, too close to a boundary, unbunded within reach of a ditch, or standing on a base that was never adequate.
Replacing the tank triggers a fresh risk assessment against current requirements. That is not bureaucracy for its own sake: a single-skin tank leaking near a drainage channel is a pollution incident, and the liability for cleaning it up falls on the property owner. Norfolk’s drainage network means a surprising proportion of rural properties fall inside the distances that require secondary containment.
So the honest position is this: a tank replacement is an opportunity to put the installation right, and sometimes that means more work than simply lifting one tank out and dropping another in. We will tell you which at survey.
How tanks actually fail
Plastic tanks
Polyethylene tanks degrade from ultraviolet exposure and from being stressed. The visible signs are crazing – a fine web of surface cracks, usually worst on the sun-facing side – bulging or deformation, and any weeping at the seams or around the fittings. A plastic tank that has been sitting on an uneven base has been under constant stress for years, and stress plus UV is how a tank that looks broadly fine develops a split.
Steel tanks
Steel tanks rust, and the important point is that they rust from the inside out. Water gets into a tank through condensation and the occasional bad delivery, it settles under the oil because it is denser, and it corrodes the base of the tank from within. By the time there is visible rust weeping through the outside, the metal at that point is thin. A steel tank with rust streaks below a seam is not a paint job.
The fittings
Sight gauges perish and split, and a failed sight tube will empty a tank onto the ground. Vent caps get lost, letting rainwater in. Outlet valves seize. Filter bowls crack. Fill caps go missing, which is both a contamination route and an invitation. These are cheaper to deal with than a tank, and worth dealing with before they become the reason you need one.
There is a fuller checklist in eight signs an oil tank is near the end of its life.
What the job involves
- Survey and assessmentCondition of the existing tank, and a risk assessment for the new one against current requirements. This decides bunding and position.
- Oil recoveryRemaining oil is pumped out. Clean oil can usually be returned to the new tank; oil contaminated with water or sludge cannot, and we will tell you which you have.
- Old tank drained, cleaned and removedIncluding the sludge layer at the bottom, which is waste and has to be disposed of as such.
- BaseEither the existing base is confirmed as adequate, or a new one is built. This is usually the largest single element of the work.
- New tank sited and fittedCorrect separation distances, correct fittings, and secondary containment where the assessment requires it.
- Oil line and fire valve renewedA new tank on a twenty-year-old supply line with a tired fire valve is a half-finished job.
- RecommissionSystem bled, boiler fired and checked, combustion verified, and everything left working before we leave.
Contaminated ground is a different and much more serious job than a tank replacement, and it can involve the Environment Agency and your insurer. If you can see or smell oil in the soil, or there is a sheen on standing water nearby, tell us at the point you call. Do not dig it over and do not hose it down – both make the situation worse.
Timing it well
The worst time to replace a tank is when it has just failed in February with a full load of oil in it. The oil has to go somewhere, the ground is saturated, and the base work is miserable. The best time is spring or summer, with the tank deliberately run low before the work, which reduces both the recovery cost and the complexity.
If your tank is over fifteen years old, the sensible thing is to have it assessed during a service visit and plan the replacement rather than react to it. We inspect the tank on every oil service as a matter of course and we will tell you honestly where yours is in its life.
Tank looking tired? Send a photograph when you call – the sun-facing side of a plastic tank, or the seams and base of a steel one, usually tell the story.
Questions we get asked about this
How long does an oil tank last?
Broadly fifteen to twenty-five years, but siting matters enormously. A plastic tank in full southern sun on a poor base will not reach the lower end of that. A steel tank that has been kept dry and painted can beat the upper end. Condition, not age, is what we assess.
Can I keep the oil that is in the old tank?
Usually. Clean oil is pumped out and returned to the new tank. If the fuel is contaminated with water or heavy sludge – which is common in a tank that is failing – putting it into a new tank would simply move the problem, so it goes for disposal instead.
Does the new tank have to be bunded?
It depends on the risk assessment for your site, not on what you had before. A great many replacements in Norfolk do require bunding, because of proximity to a ditch, drain or watercourse that was not considered when the original tank went in.
Will I need a new base?
Often, yes – either because the old base was never adequate, or because the new tank has a different footprint or position. It is the main variable in a replacement quote and we will tell you which at survey rather than on the day.
Is a leaking tank an emergency?
Treat it as one. Stop the leak spreading if you safely can, keep it away from drains and watercourses, do not wash it away, and call. Oil contamination gets more expensive by the hour and the clean-up liability sits with the property owner.
Should I move the tank while I am at it?
If the current position is compromised – too close to the house, too close to the boundary, inaccessible to the tanker, or in permanent shade and damp – then a replacement is by far the cheapest moment to move it. Moving it later as a standalone job costs considerably more.
What happens when you call
Call and describe it
You speak to an engineer, not a call centre. Most jobs can be narrowed down on the phone.
We look at it properly
A real diagnosis before a price, and a straight answer if it is not worth doing.
A written quote
Itemised, so you can see what you are paying for.
The job, and the paperwork
Certificates where the work needs them, and what will need attention next.
Where we do this work
Across Norwich and the whole of Norfolk. If you are on the edge of the county, call and ask — we will tell you honestly whether we are the right people.
- Norwich
- Wymondham
- Dereham
- Attleborough
- Aylsham
- North Walsham
- Cromer
- Diss
- Loddon
- Long Stratton
- Watton
- King's Lynn
Need this doing?
Call and describe the problem — you will speak to an engineer, not a call centre. Written quotes, no estimates over the phone.