The regulations for above-ground fuel storage on farms (greater than 4ha) require containment bunds be used where more than 2000L of petrol or diesel is stored in any one fuel tank, or there is risk of a spillage endangering any building or waterway. For other applications of fuel storage (not farms), containment bunds are required where up to 1000L or more of fuel is stored. Requirements are dependent on the location and local certifier. Your local authority should be able to advise of the requirements for single skin tanks. Mainline-manufactured containment bunds, for tanks up to and including 5000L, are manufactured from 2.5mm galvanised sheet. The 10,000L containment bunds are manufactured from 3mm galvanised sheet.