LiquaGen - Reverse Osmosis (RO) Water Storage Tank + FREE Tank Valve (20) Specifications RO water storage tank /metal tank RO water storage tank is massive capacity water storage tank (with base) Water pressure tanks are used in RO water purifier storage to prevent water pollution. Each product has been factory pressure test to meet. The water is storage between Polypropylene liner and butyl diaphragm Reverse Osmosis water filter systems or water purifiers