Automatic Shut-off Valves, also known as ASO valves, are a vital part of any efficient reverse osmosis system. RO ASO valves can save users thousands of gallons of water a year! They work by automatically shutting off production when the RO tank pressure reaches approximately 65% of the incoming line pressure, indicating that the tank is full. RO Systems without an ASO valve continually send rinse water to the drain even when the tank is full. ASO valves help to keep your system from wasting water and save you money. Fresh Water Systems will be happy to help you find the ideal reverse osmosis automatic shut off valve for your RO system. Let us help you save money on water with a brand new RO shut off valve.