When Viewing tanks on our website, you may notice the term “Nominal Dimension” listed with the tank.
As with all products, the design dimensions vs the exact dimensions of the end product you receive may vary slightly.
Due to the nature of the Rotational molding, where plastic resin is heated and rotated within a mold, there can be slight variations in wall thickness, shape, and overall size, The Australian Stardand for Poly Rainwater and chemical tanks (AS4766) allows manufacturing tolerances of up to plus or minus 3%.
So for Example a round tank 2510mm in diameter could be anywhere between 2434.7mm to 2585.3mm and still be compliant within the standards. Add to this our recommendation of having 100mm of space between the tank and any other object and you may need to allow 2785mm for that 2510mm nominal diameter tank.
Similar can be said for steel tanks, there a possibility of production variance there as well, there is no specific Australian standard that governs this but it’s still advisable to allow 100mm-200mm of additional space in any given direction for the tank.