15000-Gallon Makeup Water Storage Tank: Design, Transport And Application A 15000-gallon makeup water storage tank (roughly 56.8 m3) sits in the large-mid class: well beyond a packaged skid, but smaller than the 150-500 m3 tanks that anchor the biggest plants. It suits a sizeable cooling tower, a process line, or a multi-unit program where a multi-day buffered make-up is the planning target. This article covers sizing, transport, and the engineering choices that matter at