Thanks for the info coopersim. I'll check out the FuelProof tanks.
I've read the guidelines you linked to but there doesn't seem to be any specific detail about the way they want the base of the tank supported and the subsequent limitations of plastic and steel tanks.
This Oftec document...
My Mum's old 1200 litre steel oil tank has started to leak and we need to sort out a replacement. The current tank is only supported on two block piers.
I've been told that to simply remove the old tank and use the existing pier arrangement, we would have to use a bunded steel tank - is that...