Oil storage tanks are available in a wide range of sizes and materials. Tanks are a vital part of oil fired heating systems. The condition of the tank is therefore an important factor in the efficiency of a domestic heating system. It is recommended that oil tanks are serviced at least annually.

Common Maintenance Issues:

  • If your oil tank is unsteady or bevelled it could lead to an oil spill. This can also prove hazardous to those making deliveries to the tank. If you are concerned that your tank is in a dangerous position – seek expert advice.
  • Water entering your oil tank can cause various problems. The tank wall should be impermeable to prevent oil from spilling out and also to stop water going in. Water can also form inside the tank due to condensation in certain conditions.
  • Water will fall to the bottom of the tank and can lead to sludge formation. If that rises to a level that reaches the fuel supply line, this could prevent the boiler from operating at its maximum efficiency or it could lead to a boiler failure. It can also corrode the tank and fuel lines, which could lead to leaks. These are costly consequences of an avoidable issue.
  • Over time, plastic tank lids can go concave. This means water can fall directly into your tank.
  • In colder conditions, ice can form in the tank. Heating oil is more likely to thicken to soft wax than freeze. This could prevent the oil from reaching the boiler or clog the fuel filter.  Kerosene is unlikely to freeze in the UK as it has a freezing point of around -39°C. However, if there is water in the tank this can freeze which can cause similar problems to an oil freeze.
  • Plastic tanks can become brittle and crack after years of use. It is wise to keep an eye on the condition of the tank. This way you can replace it, if needs be, before any spillages or leaks occur.


Types of Tank

There are large tanks for commercial operations and smaller ones for domestic uses. The size, shape and material of a tank can be tailored to fit various installation requirements. If your tank is located near natural water sources, there are laws in place to ensure that tanks are contained properly. Spills are damaging to the environment and costly to clean up.

Maintenance Tips:

  • The position of your tank is important. If you are installing a new tank avoid putting it where roof rainwater runoff lands.
  • To avoid your oil freezing or waxing you could consider building a heated enclosure around your tank – this step will also reduce the risk of water entering the tank.
  • Install properly sealed fill and vent pipes on the oil storage tank.
  • Make sure your tank has a filter bowl fitted and it keep it clean to stop it from becoming clogged or blocked.
  • Have your oil filter changed each year when your furnace is professionally serviced.
  • Be alert to any oil smells near the tank and inspect the underside of above ground tanks for oil spots or drips
  • If possible, install the oil tank so that the oil tank fill pipe end is sloped downwards. This will cause water entering at the fill pipe to pool right below the filler cap where it can be observed and pumped out.
  • Keep the heating oil tank filled during warm weather. By minimizing the air space above oil in the oil storage tank you will reduce the oil tank air “exhale” as the oil tank warms, and “inhale” as the oil tank cools, thus reducing outside air and moisture being drawn into the oil tank.
  • Watch for rust or corrosion where legs are welded to the tank.
  • Regularly check the outside of tanks for rust. Clean off rust and apply rustproof paint.
  • Check the tank for problems after each fuel delivery.
  • If you have an ageing tank, a clean out may be required. Water and sludge will build up over time. If your tank is a decade old this is an advisable step.


Tank locks, gauges and fuel additives are widely recommended by oil tank manufacturers. Alarms are also available to alert you when you run low on oil.

Oil tanks are unfortunately a common target for thieves. For more information on heating oil security click here.