Secondary containment is an extra safety measure to avoid pollution of the environment or harm to people or property in case there is a spill or leak from a container or tank.

What is secondary containment?

The main container, such as a package, drum, or bulk tank, holds a hazardous liquid and keeps it safe in everyday storage.

However, if the main container breaks or leaks, a second safety system is needed. This secondary system must be able to contain the hazardous substance and safely collect it, so that no one gets hurt and no property or environment is harmed.

Different types of secondary containment can be used depending on the situation and the type of hazardous substance. Examples include spill trays, liners, double-skinned tanks, and bunds.

Secondary containment is required for all types of storage, for example, drums, packages or intermediate bulk containers (IBCs). It applies to liquids and substances that are likely to liquefy in a fire.

Secondary containment requirements in the regulations

The Health and Safety at Work (Hazardous Substances) Regulations 2017 (the Regulations) set out threshold quantities above which a secondary containment system must be provided.

The threshold quantities depend on the hazard classification of the substance and the size of the container. The threshold quantities can be found in the Regulations as follows:

• Flammable liquid, solid - Classes 3, 4: Table 9 in Schedule 9(external link)
• Oxidising - Class 5.1.1: Table 5 in Schedule 10 (external link)
• Organic peroxide - Class 5.2: Table 7 in Schedule 11(external link)
• Toxic, corrosive and ecotoxic - Classes 6, 8 and 9: Schedule 16(external link)

Secondary containment for fuel storage

Under the Regulations secondary containment is not required for storing less than 1000 litres of petrol and there are specific requirements for the storage of fuels on farms.­­

Read more: Above ground fuel storage on farms

Secondary containment calculation tool

We have a tool that can help you work out how much secondary containment you need for different amounts of hazardous substances in different storage types.

Applying to change secondary containment requirements for tanks

Our application forms relating to secondary containment are available below: