© Copyright Hi Water Concrete Tanks 2018 Concrete Top Tank (in-ground or above ground) 6x150mm columns evenly spaced and filled with Y12 vibrated concrete. Available in the following sizes 5,000, 12,000, 15,000, 23,000, and 26,000 gallon capacity. Click on the button below for detail plans. Silo Roof Option All our silo roofs are made from heavy gauge galvanised iron sheeting. Colour Bond is also available if required. Hi Water Tanks are available for in ground or above ground applications with either concrete tops or silo roofs. All Hi Water tanks are made using the highest quality materials exceeding the requirements of Australian standards. Our tanks a built to last the test of time. Tanks To Last A Lifetime.