Oil Tank Certificate When Selling

Around four million homes in the UK rely on heating oil rather than mains gas, and the vast majority of these are in rural areas. If you are selling a property with an oil-fired boiler and a domestic oil storage tank, you will need to be able to demonstrate to your buyer and their solicitor that the installation was carried out correctly and that the tank is in acceptable condition.

Unlike some areas of property disclosure, where the rules are relatively settled, oil tanks occupy a space where environmental law, building regulations, and conveyancing all intersect. This guide explains what documentation you need, what the rules are around tank siting and bunding, what an OFTEC inspection involves, and how to deal with situations where the paperwork is missing.

Why oil tanks matter when selling

A domestic oil storage tank is not simply a piece of garden equipment. It is a fuel storage installation regulated by the Building Regulations, and it carries an environmental risk that has significant implications for property transactions. If an oil tank leaks — whether from corrosion, structural failure, or damage to the supply pipework — the oil can contaminate soil and groundwater. Remediation of oil-contaminated land is expensive, disruptive, and in severe cases can cost tens of thousands of pounds.

For these reasons, buyers' solicitors take oil tanks seriously. The TA6 Property Information Form asks about the type of heating system and you will need to disclose that the property has oil heating. Once disclosed, the buyer's solicitor will almost certainly ask for documentation about the tank, its installation, and its current condition. A buyer using a mortgage will also face scrutiny from their lender, which may require confirmation that the tank is compliant and in good condition before releasing funds.

Preparing your oil tank documentation before you list — in the same way you would prepare an EPC or a boiler service record — is one of the most effective steps you can take to prevent delays and reduce the risk of sale-threatening discoveries later in the transaction.

Building Regulations and OFTEC

Oil storage tank and oil-fired boiler installations in England and Wales are governed by Part J of the Building Regulations (Combustion appliances and fuel storage systems). Work that is notifiable under Part J must either be carried out by a technician registered with a government-approved competent person scheme and self-certified, or it must be notified to and approved by the local authority's Building Control department.

What is OFTEC?

OFTEC (Oil Firing Technical Association) is the government-approved competent person scheme for oil heating installations in England and Wales. An OFTEC-registered technician is assessed and authorised to self-certify their notifiable work on oil storage tanks, oil supply pipework, and oil-fired boilers. When they complete notifiable work, they issue a commissioning certificate and notify the local authority, which then issues a Building Regulations Compliance Certificate.

These certificates are the documentation your buyer's solicitor will be looking for. If the original installer was OFTEC-registered and issued the correct certificates at the time, you should have received copies. If you purchased the property and no certificates were passed on, that is not uncommon — but it is worth trying to trace them before you list.

What work is notifiable?

The following oil installation work is notifiable under Part J of the Building Regulations:

• Installing a new oil-fired boiler, range cooker, or other oil-fired appliance
• Replacing an oil-fired appliance with a different model or type (a like-for-like replacement in the same position may not be notifiable — check with OFTEC)
• Installing a new domestic oil storage tank of any capacity
• Making significant alterations to the oil supply pipework or flue system
• Installing or replacing a bund around an existing tank

Routine maintenance such as servicing the boiler, replacing a fuel filter, or carrying out minor repairs to existing pipework does not require Building Regulations notification, but should still be carried out by an OFTEC-registered or equivalently qualified engineer.

Bunding: one of the most common issues for sellers

Secondary containment — usually in the form of a bund (a raised wall surrounding the tank) or an integrally bunded tank (where the outer shell forms the secondary containment) — is required for certain tanks under the Control of Pollution (Oil Storage) (England) Regulations 2001. This is one of the areas where many sellers discover their tank does not comply, particularly if it was installed more than 15 or 20 years ago before the regulations were tightened.

When is bunding required?

Where a bund is required, it must be capable of containing at least 110 per cent of the tank's capacity. The bund must not have an outlet pipe (which would defeat its purpose) and must be inspected regularly to ensure it is watertight. If the Environment Agency investigates an oil spill and finds that a bund was required but not present, the property owner can face significant liability for remediation costs.

If your tank requires bunding but does not have it, addressing this before you list is strongly advisable. Your buyer's solicitor will flag it, and their mortgage lender may refuse to lend until it is resolved. The cost of installing bunding around an existing tank or replacing it with an integrally bunded model varies but is typically £500 to £1,500 depending on the tank size and access.

What is an OFTEC oil tank inspection?

Even if you have the original commissioning certificate for your oil tank, buyers and their solicitors may want evidence of its current condition — particularly if the tank is more than 10 to 15 years old. An OFTEC-registered technician can carry out a formal condition inspection and issue a written report.

What does the inspection cover?

A typical oil tank condition inspection includes:

• Tank structure. Inspection of the outer body for corrosion, cracks, bulging, or signs of structural weakness. Plastic (polyethylene) tanks are less susceptible to rust than steel tanks, but they can become brittle with age and UV exposure.
• Tank base and supports. Checking that the tank is on a stable, level base adequate to support its full weight and that any legs or supports are secure and free from corrosion.
• Fill point and vent. Confirming that the fill point is accessible and correctly labelled, and that the vent pipe is clear and properly installed to prevent overfill spillage.
• Outlet and supply pipework. Inspecting the outlet valve, fire valve, and supply pipework from the tank to the boiler for leaks, damage, or deterioration, including any underground or buried sections.
• Bund or secondary containment. Verifying that any required bund is present, in good condition, and of the correct capacity; confirming that integrally bunded tanks show no signs of oil in the interstitial space.
• Siting and proximity. Checking that the tank continues to comply with the required clearance distances from buildings, boundaries, doors, windows, and water sources.

The inspection report records each of these areas along with any defects or recommendations. If the tank is in satisfactory condition, you can provide the report to your buyer's solicitor as evidence that the installation is acceptable. The cost is typically £80 to £150.

Oil tank siting rules

As well as the bunding requirements described above, oil storage tanks must be sited in accordance with specific clearance distances set out in the Building Regulations and the relevant British Standard (BS 5410). These rules apply to the installation of new tanks and to the ongoing compliance of existing tanks.

Key clearance requirements for above-ground domestic oil tanks include:

• At least 1.8 metres from any non-fire-rated building opening (doors, windows, vents) and at least 760 millimetres from a non-fire-rated eaves
• At least 1.8 metres from a non-fire-rated boundary (including fences, hedges, and walls)
• At least 600 millimetres from a building with a fire-rated wall
• At least 760 millimetres from any fixed ignition source (such as an outdoor electrical socket)

In practice, many older tank installations were positioned before these rules were codified, and may not comply with current clearance requirements. A non-compliant siting does not automatically prevent a sale, but it will be flagged in an inspection report and the buyer's solicitor will raise it. Depending on the lender and the buyer's stance, it may need to be rectified or addressed with indemnity insurance.

What happens when documentation is missing?

Missing commissioning certificates are common, particularly for oil tanks installed more than a decade ago or inherited from a previous owner. If you cannot produce a commissioning certificate or Building Regulations Compliance Certificate for your tank, here is how to approach it:

1. Check with the original installer. If you know who installed the tank and they are still trading, contact them. OFTEC requires registered technicians to retain records. Alternatively, search the OFTEC contractor database at oftec.org using the installer's name or company.
2. Check with Building Control. If the installation was notified to your local authority, they will hold a record of the Building Regulations Compliance Certificate. Contact them with the property address and approximate installation date.
3. Obtain a current condition inspection report. This is the most practical solution in most cases. Commission an OFTEC-registered technician to inspect the tank and issue a written condition report. If the report confirms the tank is in good condition and compliant with current requirements, many buyers' solicitors and lenders will accept this in lieu of the original commissioning documentation. For more on handling missing building regulations paperwork generally, see our guide on missing Building Regulations sign-off.
4. Apply for retrospective Building Regulations approval. Under Section 36 of the Building Act 1984, you can apply for a regularisation certificate from Building Control. This involves an inspection of the work (which may require exposing buried pipework) and, if satisfactory, the issue of a regularisation certificate. This is more time-consuming and costly than a simple inspection report but provides a formal compliance document.
5. Indemnity insurance. Your solicitor may suggest indemnity insurance to cover the risk of the local authority taking enforcement action against non-notified installation work. Premiums for oil tank indemnity policies are typically £100 to £300 as a one-off payment. However, indemnity insurance does not confirm the tank is safe or compliant — it only covers the enforcement risk — and some mortgage lenders will not accept it for oil tank issues. See our guide on hidden costs of selling a house for more on the types of insurance and other unexpected expenses that arise during a sale.

Oil tank disclosure on the TA6 form

The TA6 Property Information Form is the main disclosure document in an English or Welsh property sale. When completing it, you will need to provide accurate information about your heating system, including the fact that the property uses oil heating. The services section asks about the type of central heating system, and you should state that it is oil-fired.

Your solicitor or the buyer's solicitor is likely to ask follow-up enquiries about:

• Whether the oil storage tank is above-ground or underground
• The age and capacity of the tank
• Whether the tank is bunded
• Whether there are any known leaks or contamination
• Whether you have commissioning certificates or Building Regulations documentation for the tank and boiler installation
• When the boiler was last serviced and whether you have service records

Being honest and thorough in your responses is essential. Providing false or misleading information on the TA6 can expose you to a claim from the buyer after completion. If you are aware of any issues with the tank — for example, a previous minor leak that was addressed, or the absence of bunding that should be present — you must disclose this. Proactive disclosure allows you to control the narrative and demonstrate that you have taken appropriate action, rather than having issues emerge unexpectedly during the transaction.

Underground oil tanks: additional considerations

Underground oil storage tanks are less common in domestic properties than above-ground tanks, but they do exist, particularly in older rural homes. They are significantly more complex to assess and more expensive to deal with if problems are found.

The key risks with underground tanks are:

• Corrosion. Steel underground tanks corrode from the outside as well as the inside. A tank that appears to be functioning normally can have significant corrosion that is not visible above ground.
• Leakage. An underground tank that has been leaking slowly can contaminate a large volume of soil and, potentially, groundwater without any visible sign at the surface.
• Remediation cost. If contamination is found, remediation can be extremely expensive — in serious cases running to tens of thousands of pounds. Mortgage lenders will generally decline to lend on properties with known oil contamination until it has been remediated.

If your property has an underground oil tank, you should arrange a specialist underground tank survey before marketing. This typically involves a survey of the tank using video equipment and soil testing around the tank to check for contamination. The cost is higher than an above-ground inspection — typically £300 to £800 depending on access and the scope of testing. If the tank has not been in use for some years, it may be advisable to have it decommissioned and removed before sale, as an unused underground tank is often viewed as a liability by buyers and lenders.

Boiler service records alongside tank documentation

An oil tank inspection report tells buyers about the condition of the fuel storage, but they will also want to know about the oil-fired boiler. A current boiler service record, ideally from an OFTEC-registered engineer, provides reassurance that the boiler is operating safely and efficiently. Taken together, an oil tank inspection report and a boiler service record give buyers and their solicitors a comprehensive picture of the oil heating system.

The principle is the same as with gas heating — for guidance on the equivalent situation for gas properties, see our guide on boiler service records when selling. For oil heating, the boiler service should be carried out by an OFTEC-registered technician who is qualified in oil appliances. During the service, they will clean and inspect the burner, check the oil filter and pump, inspect the flue and combustion chamber, test the safety controls, and carry out combustion efficiency tests. A service report records the findings and confirms that the boiler is safe and performing within acceptable parameters.

How oil tank issues affect conveyancing

Oil tank issues can arise at several stages of the conveyancing process, and understanding where they are likely to surface helps you prepare:

1. Pre-contract enquiries. Once the draft contract pack is sent to the buyer's solicitor, they will raise enquiries about anything not covered or clarified by the TA6 form or supporting documents. Missing oil tank certificates are routinely raised as formal enquiries. Each round of enquiries and responses can add one to two weeks to the timeline.
2. The buyer's survey. A surveyor will note the presence of an oil tank in their report. They may flag obvious issues such as visible corrosion, absence of bunding, or concerns about siting. If the surveyor recommends further investigation of the tank, the buyer may commission a specialist inspection at your expense or use their findings to negotiate a price reduction.
3. Environmental searches. The environmental search carried out by the buyer's solicitor may flag the property as being in an area with recorded oil contamination. This does not necessarily mean your tank has leaked, but it will prompt further scrutiny. See our broader guide on what is in a property certificate pack for more on the searches conducted during a sale.
4. Mortgage lender requirements. If the buyer is using a mortgage and the lender's valuer or the buyer's survey raises oil tank concerns, the lender may impose conditions before releasing funds. These can range from requiring a satisfactory tank inspection report to requiring contamination testing or the installation of bunding. Lender conditions at a late stage can significantly delay completion.

Seller's checklist for oil tank preparation

Use this checklist to ensure your oil tank documentation is in order before you list your property:

1. Locate any commissioning certificates or Building Regulations Compliance Certificates for the tank installation and boiler
2. Establish whether the tank requires bunding under the Control of Pollution (Oil Storage) (England) Regulations 2001 and, if so, confirm it is compliant
3. Arrange an OFTEC oil tank condition inspection if the tank is more than 10 years old or if you have any concerns about its condition
4. Book an oil boiler service to obtain a current service record from an OFTEC-registered technician
5. If the tank is underground, arrange a specialist underground tank survey including soil contamination testing
6. Address any issues identified in the inspection (bunding, siting, corrosion, pipework) before listing where possible
7. Confirm that your home insurance policy covers the oil tank and the risk of oil leakage
8. Complete the TA6 form accurately, disclosing the oil heating system, tank details, and any known issues, and attach all certificates and reports
9. Provide all documentation to your solicitor so it can be included in the draft contract pack sent to the buyer's solicitor

Sources

• OFTEC (Oil Firing Technical Association) — oftec.org
• Control of Pollution (Oil Storage) (England) Regulations 2001 — legislation.gov.uk
• Approved Document J: Combustion appliances and fuel storage systems (2010 edition with 2013 amendments) — gov.uk
• BS 5410-1: 2014 Code of Practice for Oil Firing — BSI
• Environment Agency: Storing oil at your home — gov.uk
• Building Act 1984, Section 36 (regularisation of unauthorised work) — legislation.gov.uk
• Law Society — Property Information Form (TA6), 4th edition
• Health and Safety Executive (HSE) — Domestic oil storage: guidance for householders

Frequently asked questions