How Bunded Oil Tanks Work: A Guide For Homes and Businesses

If you store heating oil at your home, farm, or business, choosing the right tank is essential for both safety and compliance. One of the most reliable and widely recommended options is the bunded oil tank. At Tanks R Us, we supply high-quality bunded tanks designed to protect the environment, safeguard your fuel, and meet UK regulations. This guide explains what a bunded tank is, how it works, why it’s required in many cases, and how to choose the right one for your needs.

What Is a Bunded Oil Tank?

A bunded tank is essentially a “tank within a tank.” The inner tank holds the oil, while the outer shell, known as the bund, acts as a protective barrier. If the inner tank leaks or overflows, the outer layer captures the spilled oil, preventing it from escaping into the ground or nearby watercourses.

The bund should be able to contain at least 110% of the inner tank’s capacity, offering a vital layer of safety. This dual-layer design significantly reduces the risk of pollution, property damage, and costly clean-up operations in the event of a leak or split.

Why Bunded Tanks Are the Safer Choice

A standard single-skin tank can store oil effectively, but it provides no secondary containment if something goes wrong. A bunded tank, by contrast, is engineered to stop leaks before they become environmental hazards. Here are some of the key benefits:

• Environmental Protection – Leaked oil can contaminate soil and water, causing serious ecological damage. The outer bund ensures that even if a failure occurs, the oil is contained.
• Legal Compliance – In many cases, bunded tanks are required by law (for example, commercial sites, farms, and properties near drains, watercourses, or boreholes).
• Reduced Fire and Safety Risk – Contained spills lower the risk of ignition and improve site safety overall.
• Longer Lifespan – Bunded tanks are more robust and resistant to impact, corrosion, and UV damage.
• Peace of Mind – Knowing your tank meets environmental and safety standards helps you avoid fines, clean-up costs, and stress.

At Tanks R Us, our bunded oil tanks are built to high manufacturing standards, offering durability and performance in demanding environments.

When You Need a Bunded Oil Tank

UK environmental regulations set out specific conditions under which bunded storage is required. According to the Oil Storage Regulations for England (Control of Pollution 2001), you must use a bunded tank if:

• You’re storing more than 200 litres of oil commercially, or
• You’re storing over 3,500 litres of oil for domestic use, or
• The tank is located within 10 meters of a watercourse (e.g., stream, ditch, or drain), or
• It sits within 50 meters of a well or borehole, or
• It’s in a location where a spill could enter drains or contaminate soil.

Even if your setup doesn’t strictly require a bunded tank by law, it’s still the best choice for protecting both your property and the environment. Many insurance providers now insist on bunded tanks as part of their cover requirements.

Construction and Design Features

A quality bunded tank isn’t just about two layers of plastic. The design and materials used play a crucial role in longevity and safety. Most modern bunded tanks are constructed from UV-stabilised, rotationally moulded polyethylene, which is strong, weather-resistant, and corrosion-proof.

Here are the main components and features you’ll typically find on a bunded tank:

• Lockable Lid – Protects the fill point and prevents unauthorized access or contamination.
• Bund Outlet and Drain – Allows safe emptying and inspection of the bund if required.
• Overfill Prevention Valve – Helps stop accidental spillage during refilling.
• Level Gauge – Indicates how much fuel remains, helping avoid overfilling.
• Vents and Filters – Maintain proper airflow and fuel quality.
• Inspection Hatch – Provides easy access for maintenance and cleaning.

Every Tanks R Us bunded oil tank is manufactured with durability in mind, combining robust materials with smart engineering to deliver long-term reliability.

Installation Requirements

A safe installation is just as important as the tank itself. Bunded tanks must be positioned on a solid, level base made from non-combustible material—such as concrete, paving slabs, or a reinforced platform. The base should extend at least 300mm beyond the footprint of the tank on all sides.

Key installation considerations include:

• Distance from Buildings – Follow manufacturer and fire-safety guidance to ensure safe clearance.
• Accessibility – Leave enough space for inspection, maintenance, and refilling.
• Bund Clearance – Ensure the outer bund is unobstructed and can contain a full spill if needed.
• Pipework – Use approved fittings and ensure all connections are leak-proof.
• Security – Tanks should be installed in secure areas to prevent theft or tampering.

Tanks R Us can guide you through installation requirements to ensure compliance with both OFTEC and environmental standards.

Maintenance and Inspection

To keep your bunded tank performing safely and efficiently, regular inspection is essential. Visual checks should be carried out every few months to look for cracks, corrosion, or signs of oil around the bund area.

Once a year, you should arrange a professional inspection to confirm the bund’s integrity, check for water ingress, and verify that fittings and seals are secure. If any part of the tank shows damage or deformation, it should be repaired or replaced immediately.

Tanks exposed to direct sunlight or harsh weather may also benefit from additional UV protection or a tank cover to extend their lifespan.

Choosing the Right Bunded Tank from Tanks R Us

When selecting a bunded tank, consider the following factors:

• Capacity – How much oil do you need to store? Domestic users often choose between 1,000 and 2,500 litres, while commercial or agricultural setups may require 5,000 litres or more.
• Material – Plastic tanks are lightweight and corrosion-resistant; steel tanks offer even greater durability for industrial use.
• Location – Outdoor installations should use UV-stabilized materials and weatherproof fittings.
• Features – Options such as gauges, alarms, and pumps can make fuel management easier.

At Tanks R Us, we supply a wide range of bunded oil tanks from trusted UK manufacturers, suitable for both domestic and commercial applications. Whether you’re replacing an old tank or installing a new system, our team can help you choose the right model to meet your capacity, site, and budget requirements.

The Bottom Line

A bunded oil tank is an investment in safety, compliance, and environmental protection. While single-skin tanks may appear cheaper initially, the long-term risks far outweigh the savings. With a bunded system, you reduce pollution risk, meet legal standards, and gain peace of mind that your heating oil is stored securely.

At Tanks R Us, we make it simple to find the right bunded tank for your property. Our products are durable, fully compliant, and built for performance. Explore our full range of bunded oil tanks today or contact our team for expert advice on choosing the ideal solution for your needs.