Aqua Pure PRO-20G 75 Liter Reverse Osmosis Water Tank Reverse osmosis systems usually have a small water output, it depends on the membrane installed in the system and the user of the filter will have to wait a long time to fill a glass with water , the solution is provided by the water storage container that ensures a constant flow of water. Features: Container capacity 75 Litres. Vacuum: 0.5 bar