FAQs on oil storage tanks
What types of oil storage tanks are available?
There are three generic types of oil storage tanks available for use in different applications such as single skin (which may be installed in a reinforced concrete or masonry bund), double skin (predominantly commercial underground applications (USTs)) and integrally bunded (above ground and within buildings). Oil storage tanks are constructed of steel or polyethylene and can be supplied in a range of shapes and sizes to suit the site requirements.
For details of tank manufacturers and the various types of tanks available please see the OFTEC Equipment Directory.
What is a bund?
A bund (or catchpit) is a secondary containment system designed to prevent fuel loss from the tank escaping to the environment. Bunds may be constructed from masonry or concrete (see CIRIA Report 163) to contain a single skin oil storage tank and must be able to hold at least 110% of the tank’s contents in the event that a leak or overspill occurs. Integrally bunded oil storage tank systems are available and provide a practical solution to satisfying environmental protection requirements.
For bunds constructed from masonry, please see CIRIA Report 163.
For bunds constructed from concrete, please see CIRIA Report 163.
For details of tank manufacturers and the various types of tanks available please see the OFTEC Equipment Directory.
Does a domestic oil storage tank require secondary containment (bunding)?
Building Regulations for England and Wales requires all domestic oil storage tanks exceeding 2500 litres capacity to be provided with secondary containment (bunding). The bunding of oil tanks not exceeding 2500 litres capacity is dictated by the outcome of an individual site pollution risk assessment. Only when there is no risk of oil reaching for example, a watercourse, water extraction point or aquifer following a release of oil from the tank may a single skin tank be considered.
Your local OFTEC Registered tank installer will be able to perform a fire and pollution risk assessment and advise on the type of tank most suitable for an installation.
For details of OFTEC Registered Technicians that operate local in your area, please see Locate a Registered Company.
What is controlled water?
Controlled Waters can be defined as the following:
Rivers, streams, lakes, canals, coastal waters, estuaries and groundwater. This means all water which is below the surface of the ground in the saturation zone and in direct contact with the ground or subsoil.
For the purposes of an oil tank pollution risk assessment, consideration should also be given to any ditches, soakaways, septic tanks and gullies which could pollute groundwater or reach controlled waters. Environment Agency defined Special Protection Zones (water abstraction points and aquifers) should be equally protected.
What fire separation distances apply to domestic oil storage tanks?
For details surround fire separation requirements for domestic oil storage tanks serving fixed combustion appliances, please see the OFTEC Easy Guide to Domestic Oil Storage.
What fire separation distances apply to non-domestic oil storage tanks?
For details surround fire separation requirements for non-domestic oil storage tanks serving fixed combustion appliances, please see the OFTEC Easy Guide to Non-Domestic Oil Storage.
What fire separation distance is required from an oil storage tank to LPG cylinders?
For latest guidance regarding the safe storage of LPG cylinders in relation to oil storage tanks, reference should be made to the UKLPG User Information Sheet 010.
Can screening be erected to disguise an oil storage tank from view?
Yes, screening of domestic oil storage tanks is permitted. However, consideration should be given to providing service access for inspection of the tank and filter maintenance, etc. British Standard 5410: Part 1: 1997 (see OFTEC Technical Book 3) requires that a minimum of 600 mm separation be provided between a tank and screening. If the screening forms part of the property boundary a 760 mm separation should be provided unless a fire barrier is erected.
OFTEC Technical book 3 can be purchased from OFTEC Direct.
Can a domestic oil storage tank be installed internally?
Yes, British Standard 5410: Part 1: 1997 (see OFTEC Technical Book 3) does permit a domestic oil storage tank up to 3500 litres capacity to be installed within a building so long as the tank is provided with secondary containment, such as an integrally bunded oil storage tank, contained within a 60 minute fire resistant chamber and is located at the lowest possible level. The chamber should contain nothing but the tank and be ventilated to outside.
OFTEC Technical book 3 can be purchased from OFTEC Direct.
Can a domestic oil storage tank be installed underground?
If an underground oil storage tank is to be directly buried below ground it should be specifically constructed for underground use and should be installed strictly to the manufacturer’s instructions. In addition, the recommendations in Pollution Prevention Guidance note PPG 27 should be followed and planning permission may also be required.
Please see PPG 27
If an oil storage tank is removed from its base temporarily, for example to repair the base and piers, would I be allowed to reinstall the original oil storage tank as it was before or would I have to treat this as a new installation?
Yes, but OFTEC would recommend that all oil storage tank installations should be compliant with regulatory requirements and industry guidance. However, the installation of a ‘new’ or ‘replacement’ oil storage tank would fall within the scope of the Building Regulations.
Is the support offered by the oil storage tank base really that important?
Yes, the need to provide stable bases and supports for domestic oil storage tanks both of steel and plastic construction is of paramount importance for reasons of both safety and environmental protection. If an oil storage tank is inadequately supported the oil storage tank itself can be weakened leading to the eventual failure of the oil storage tank and escape of the stored fuel. During the life of an installation an oil storage tank base will need to provide continual structural support even though ground conditions may alter from season to season and year to year.
What material should the oil storage tank base be constructed of and what dimensions does it need to be?
Types of base materials, as listed in British Standard 5410: Part 1: 1997 (see OFTEC Technical Book 3) to achieve this protection, include concrete of at least 100mm thickness, paving stones of at least 42mm thickness or stonework of at least 42mm thickness (all laid on a hardcore base to give an imperforate base). The overall size of the base should be larger than the oil storage tank and any integral oil storage tank bund, so that when the oil storage tank is installed, the base has a clear projection of a minimum of 300mm around all sides of the oil storage tank.
OFTEC Technical book 3 can be purchased from OFTEC Direct.
Why is the tank base required to extend 300mm around the perimeter of the oil storage tank?
The fire protection provided by the base, is to help prevent the installation itself from becoming overgrown and to help protect against fire spreading across the ground to the contained fuel, from another source. If the tank is raised on piers, the platform supporting the tank should be sized to sufficiently support the tank. Reference should be made to the tank manufacturer’s installation instructions.
What is the purpose of a remote fill pipe?
Remote fill pipes are provided for oil storage tanks sited in excess of 30m from a road, or where there is restricted access generally. For domestic installations this would generally take the form of a 50mm steel pipe connected to the tank and routed to an accessible position. The pipe should incorporate a screw cap at the fill point, a gate valve, a non-return valve and be adequately supported.
Due to increased risk of spillage during filling process, the tank it serves should have secondary containment, such as an integrally bunded oil storage tank, and should be fitted with and overfill prevention device. An audible overfill alarm is also recommended.
Further help
We also produce a series of FREE downloadable Easy Guides. You may find one of these is helpful.
If you can’t find the answers you are looking for here you can contact the OFTEC Technical Helpline on 0905 757 0135 (calls are charged at 95p a minute, but some service providers may vary) and speak to a member of the OFTEC Technical Team.
Alternatively, you can send in a technical enquiry form. We aim to respond to technical enquiry e-mails within 3 working days.