RO System Water Storage Tanks
Typical under-counter reverse osmosis systems include a bladder water storage tank to hold treated water until a faucet is turned on to deliver water for consumption. When the faucet is turned on, compressed air in the water tank acts like a spring: it pushes on the bladder and water is pushed out of the bladder in the water tank to the faucet. As water leaves the storage tank, water pressure in the water tank drops.
A pressure control switch, usually mounted on or near the water tank, senses the pressure drop; and at a pre-set "cut-in pressure" (typically 20 or 30 psi), the pressure switch activates the RO system. As the RO system produces additional treated water, water is delivered to the bladder in the storage tank and pressure in the tank is increased. The pressure control switch turns off the RO system when water pressure in the pressure tank reaches the "cut-out pressure" (typically 40 or 50 psi).