Heating oil tanks

Heating oil tanks are made from fabricated steel or plastic and can be installed inside, outside or underground. Keeping your tank and system well maintained will keep them as efficient as possible, which will, in turn, help keep your costs down and reduce the risk of it breaking down.

The oil in your tank is valuable, so it’s also important to protect it from theft as best you can.

If you're thinking of updating your heating system, see our oil boiler reviews to find out which have been rated the most reliable by customers and heating engineers. 

Grants to change to renewable heating are available via the government's Boiler Upgrade Scheme.

Heating oil tanks: the essentials

Heating oil tanks can be single skinned, double skinned (where the tank has two layers) or integrally bunded (with a protective layer).

Integrally bunded tanks have one tank sitting within another, with the outside tank housing the main tank's fittings and vents. These tanks give better protection than double-skinned tanks, as there is more room between the two layers to prevent oil leaking externally. 

See our image gallery below for more information.

Most single-skinned and double-skinned tanks need to have a bund built around them for protection, although this will depend on where you live and the position of your tank. The bund can hold 110% of the capacity of the inner tank.

Your heating oil tank should be at least 1.8 metres away from doors and windows and on a solid, sturdy base that extends at least 30cm beyond the tank on all sides.

Heating oil tanks should last up to 20 years with maintenance. If yours is nearing the end of its life, it's worth replacing it to avoid any leaks. 

Where can I buy a heating oil tank?

Heating oil tanks are available online and through local independent companies. 

Before you purchase a tank, check that it's manufactured to meet the standards of trade organisation Oftec (Oil Firing Technical Association). An Oftec-registered technician can help you choose the type of tank and where to put it so that it complies with location regulations (to limit environmental and fire risks) and building regulations, both of which vary across the UK.

Use the Oftec website to find a technician in your area, or visit Gov.uk for more information.

Heating oil tank prices

Prices generally range from around £450 for a small single-skinned tank to more than £4,000 for a large integrally bunded one. 

Price also depends on size, which can vary from around 650 up to 10,000 litres for home heating.

How much heating oil should I order?

1,000 litres could last for six months to a year, but it depends on a number of factors, such as:

• the size of your home
• how many radiators you have
• how much you have your heating on
• whether your oil boiler is efficient.

Try to work out how much heating you use in your household by keeping tabs on your tank gauge over time. All heating oil tanks should have a gauge to indicate how much oil is left in the tank. This may be on the tank, next to it, or displayed remotely. There are also smart gauges that let you monitor your oil levels using a smartphone app.

If your tank doesn't have a gauge, you can buy one separately. They cost from around £25 for a basic gauge, to more than £400 for a digital remote one. 

Keep an eye on your oil tank gauge so your supply doesn't get too low. Make sure you order more oil before it becomes less than a quarter full, especially in the winter. 

You should only fill your tank to around 80-90% of its capacity, to avoid spillages. 

Don't pay more than you have to for heating oil. See our advice on how to get the best price for heating oil.

How often should my heating oil tank be serviced?

You should have your tank inspected at least once a year by an Oftec-registered technician to make sure it's in good condition and safe to use. Inspections cost around £70 to £100, and should check:

• pipework
• the integral bund
• gauges
• valves
• oil filters
• air vents.

If you've moved into a new property and ‘inherited’ your heating oil tank, it's worth arranging an inspection as soon as possible.

Steel tanks have an oil-resistant coating, which needs to be maintained to prolong the life of the tank. Check with the manufacturer to find out what maintenance is needed besides annual servicing. 

You should also have your oil boiler serviced annually. Find a trusted local engineer using Which? Trusted Traders.

Heating oil tank checks you can do yourself

Besides getting your oil tank serviced annually, there are simple checks and precautions you should take to make sure your tank is in good condition, such as:

• checking for damage, such as bulges, deep scratches, cracks, discolouration, rust or major dents
• looking out for any oil that has leaked out, particularly around pipes, valves and seams
• making sure that any external protection, such as a bund (scroll up to find out more), isn't filled with water, oil, rubbish or weeds
• keeping access to and around the tank clear
• ensuring vents, gauges and access points are closed and protected so that rainwater, insects or dirt can't get in
• checking that gauges and alarms are working correctly, including their batteries. Consult the manufacturer for advice on how to do this
• keeping an oil-spill kit with drain blockers, leak-sealing putty and absorbent materials
• making sure your tank is only filled to around 80-90% of its capacity and ensuring that your tank has an overfill protection device or alarm.

What to do if your heating oil tank leaks

Oil is toxic and harmful to the environment, including animals, plants and water sources. If you spot a leak, put a bucket under it straight away and turn off the tap to stop the flow. In some cases you may be able to smell oil but not see where it's coming from. Defects should be fixed immediately by a professional.

You should report an oil spill by calling the Environment Agency incident hotline on 0800 807060 (England, Scotland and Northern Ireland) or Natural Resources Wales on 0300 065 3000 (Wales). 

You're legally responsible for cleaning up any oil spills. This can cost tens of thousands of pounds, so check that your home insurance:

• covers the cost of replacing lost, leaked or stolen oil
• covers environmental clean-up
• has a high enough liability limit to cover the cost of cleaning up your property or neighbouring land.

You may need to take out standalone insurance to be sufficiently covered. 

Not all insurance policies cover oil leakage. See our guide to home insurance for more information, and to find out which insurance companies are highly rated by customers.

Heating oil tank problems: sludge, water and cold weather

If sludge or water get into your tank, they can clog up the pipework, damage your heating system and reduce the efficiency of the oil. 

Water might get in if it’s raining when your oil is delivered, or from condensation. Sludge tends to build up in tanks where oil has been stored for a long time.

Look for signs of a darkened area at the bottom of the tank. This can be caused by erosion due to sludge. You can also buy water-finding paste, which changes colour if water is present. 

A technician can remove water and sludge and clean your tank, as well as fix whatever's causing the problem.

Heating oil doesn't freeze into a solid lump. However, in very cold weather (usually -39°C), heating oil can ‘wax up’, which means it forms crystals that stop it from flowing as easily. Kerosene is less likely to become waxy than gas oil. 

If you use gas oil, you can buy additives to help prevent crystals forming. These cost around £30 for a litre, which treats 1,000 litres of oil.

Heating oil theft

Heating oil is pricey, so it can be attractive to thieves. Adding locks or lockable caps will help to prevent theft. 

Shield your tank so it isn't visible from the road. But make sure its position still complies with guidelines and access to it isn't restricted. Ask an Oftec-registered technician for details.

You could also install motion-sensitive security lighting to alert you if there's a problem, or an alarm that will react if the oil level drops suddenly (these cost from around £100). Plus they're useful for notifying you of an oil leak.

It's cheaper to order your heating oil in bulk, though this can mean that you have more to lose if it's stolen. Find out more about bulk buying in getting the best price for your heating oil.

Your rights with heating oil suppliers: FAQs

Q: The supplier changed the price of my heating oil order before it was delivered. What should I do?

Check the terms and conditions of your purchase. Some specify that the contract isn't formed until the oil is dispatched. 

If the contract allows for the price to be increased after it has been agreed, it should generally give you the right to cancel if the new price is too high.  

Always ask for a written confirmation of your order so you don't get a surprise when you get your bill. Written confirmation should include:

• the amount of oil you're ordering
• the price
• delivery timescales.

Ordering over the phone is classed as a distance selling contract, so your supplier must give you certain information, such as the price agreed. Where this isn’t possible, it should show how the price will be calculated, as well as any additional payments.

The 14-day cooling-off period for distance selling under the Consumer Contracts Regulations won't apply to heating oil once it's been put into your tank. Find out more in our guide to the Consumer Contracts Regulations.

Q: The oil delivered is sludgy. What should I do?

If the oil delivered is sludgy and unusable, you have the same consumer rights as with most other goods and services under the Consumer Rights Act. 

Find out how the Consumer Rights Act can help if you're having problems with your heating oil order.