Slimline Rainwater Tank Dimensions: 700mm x 1700mm x 1860mm (SL-0700-1700-1860). Kingspan's 2,000 Litre Slimline AQUAPLATE Steel Water Tank with beautifully curved ends can service gardens, drinking purposes, or be used as a header tank. AQUAPLATE is a BlueScope steel specifically designed for use in rainwater tanks and storing drinking water. The corrugated steel tank has an inner poly layer fabricated to a galvanised steel substrate, while the outer layer consists of a COLORBOND laminate coating.