Haitun Water Pressure Control Switch 30-50 PSI 110V, 220V Single Port {Mechanical Well Pump Switch}(Square D Type)

I used this to control my reverse osmosis system. You can set the cutoff pressure and the turn pressure. Use a 9vdc power supply and a time delay module, plus a couple 12v water solenoid valves and a check valve to make a control system to dump the water sitting in the membrane with the high TDS down the drain. It takes about 4 min then stops the drain connection and fills the pressure tank. When pressure is reached control cuts off and system waits till pressure drops to start again . Best RO water I have had, NO TDS creep from 630ppm TDS to 19ppm.

Great product I will never use any other brand of pressure control switch again. Fully adjustable on the cut in and cut out. Easy to install and maintenance free.