Should I Choose a Single-Skin or Bunded Tank?

Choosing the right oil tank for your property might seem like a daunting task due to the numerous shapes, sizes and capacities available, but perhaps the first decision you should make before investing is whether to install a single-skin or bunded tank. 

While with commercial installations, or for any oil storage tanks above a 2500 litres in capacity, there is no option but to choose a bunded tank. With standard domestic installations, however, the requirements are a little more complex. 

Oil tank installations are classified as notifiable works by Building Regulations and homeowners must ensure they are installed in accordance with current legislation. This might mean checking with the Building Control Department or with your local council. Let’s take a look at some of the benefits of choosing either single-skin or bunded oil tanks.

Bunded tanks

Bunding or secondary containment can be achieved using two methods. The first option is a single-skin tank which is installed in an open bund built from masonry and sealed with an oil-proof render. This bund is required to hold 110% of the primary tank’s capacity. The downfall of this approach is that the bund is susceptible to filling up with rainwater, leaves and general garden debris. This can result in the need for ongoing maintenance, and if the water becomes contaminated, it will need to be taken away and disposed of as contaminated waste—an unhelpfully costly exercise. 

The second option, one which our team of expert tank installers would always recommend, is an integrally bunded tank—a tank within a tank—which features a sealed bund. While the inner tank stores the oil, the outer tank protects the inner layer, offering a secondary level of security against potential spillages or leaks. So, even in the unlikely occurrence of an inner layer leak, no oil will ever leave the tank and cause costly and environmental damage.

Bunded fuel tanks with a secure slab or concrete base are a hugely popular oil storage option which negates the risk of groundwater pollution, and, when installed by our experienced team, you can be sure it's done in compliance with the Environmental Agency’s regulations. A bunded tank also offers more flexibility with the installation location on your property.

Single-skin tanks

There are a number of benefits associated with choosing a single-skin tank, from its lightweight properties, its ease of installation, UV stabilisation, and lower price point. A single-skin tank also requires very little in the way of maintenance once the installation is complete. 

However, before making the decision between a single-skin or bunded tank, it’s always advisable to have a risk assessment carried out by a qualified engineer. As discussed, there will be particular circumstances where a bunded tank will be legally necessary. If you need a tank capacity of more than 2500 litres or if the tank will be positioned within 10 meters of a controlled water source, you will require a bunded tank.

As a general guide, you should only choose a single-skin tank if the following criteria are met:

• The capacity of the oil tank is less than 2500 litres
• The tank must is not within 10m of a controlled water source, including rivers, streams, and ditches.
• The tank is not located where a leak could run into an open drain or loose-fitting manhole cover 
• The tank is not located within 50m of a well, borehole or spring.
• The tank is not installed over hard ground which could result in spillage runoff to a controlled water source.
• The location of the tank doesn’t allow visibility from the fill point 
• The tank doesn’t supply heating oil to a building other than a single-family dwelling 
• The tank isn’t located within a Ground Source Protection Zone 1
• There are no other potential environmental hazards
• Your home insurance policy doesn’t require a bunded tank

If you can confidently meet all of these requirements, then a single-skin tank can be installed.

How can CT Tanks help?

Whether you require a single-skin or bunded oil tank for your property, CT Tanks can guarantee that the installation is done efficiently, professionally, and safely, while ensuring that all OFTEC building regulations and environmental legislation are met. For any advice on choosing the right oil tank for your home, please don’t hesitate to get in touch.