The reverse osmosis process is on the slower side, so a pressurized storage tank is typically required to supply water from the system on demand. Your RO system will fill the tank to capacity, and when you open your RO water dispenser the water is sent out by the tank’s pressurized air bladder. The concern that pollutants may be allowed in when using an open air tank favors the use of a closed expansion tank such as the T32M. The tank uses stainless steel connections to avoid any leaching concerns, tested by independent third-party to meet NSF/ANSI Standard, and is CE approved under the PED (Pressure Equipment Directive).