NSF Certified 4.0 Gallon Water Storage Tank (3.2 gallon draw-down) Description Water goes through a reverse osmosis membrane very slowly and people don"t have the patience to wait a long time to get a cup of water. For this reason the residential RO units need a water storage tank to store the purified water. The RO tanks can delivery stable and constant water flow when the faucet is opened. The concern that pollutants might come from air or animals with the use an opened tank favors the use of a closed expansion tank. Lead leaching to drinking water the cause of health risks, brass and copper are banned for use in purified/drinking water. This tank uses stainless steel connections to avoid the lead leaching concerns. This tank is NSF approved under standard 58, and CE approved under the PED (pressure equipment directive). Features - Stainless steel connection built for Reverse Osmosis water storage tank; pump tank & thermal tank applications. - Smooth internal air vent cap prevents diaphragm damaged. - High-grade butyl diaphragm, post-cure procedure insures a tasteless and odorless water chamber - NSF 61 and 58 listed. - IAMPO approved. - CE Mark approved TANK BALL VALVE NOT INCLUDED Specifications & Dimensions - Height: 14", Diameter: 11" - Actual tank size: 4.0 gallons - Tank storage capacity: 3.2 gallons - Shipping weight: 9 LBS.