Series PWR4021 Reverse Osmosis (RO) Systems are commercial grade high-pressure RO units for the reduction of total dissolved solids from water. They are designed to supply reverse osmosis quality water with production rates ranging from 3,600 to 10,800 gallons per day. These units are designed for floor mount installations. Reverse osmosis is a process where high-pressure feed water is fed into a semi-permeable membrane. In the membrane, pure water is allowed to pass through the membrane material and exit as purified permeate water. Dissolved mineral salts are not allowed to pass through the membrane and become a concentrated reject stream that is sent to drain. These RO systems use high-pressure/high-rejection membranes to achieve a minimum average NaCl ionic rejection of 95 percent. Includes membrane auto flush and 20-in. high flow pre-filter. Other features include powder coated carbon steel support frame, 316L stainless steel 300 psi high-pressure membrane housings, pressure gauges for pre-filter inlet/outlet, membrane feed, and reject water pressure, low feed water pressure safety switch, digital microprocessor based controller with delayed auto restart after low-pressure shut down, permeate water conductivity meter with high-conductivity alarm output, tank level and pretreatment interlock inputs, permeate, reject recycle, and reject water flow meters, adjustable reject and reject recycle valves, permeate check valve, and automatic inlet solenoid valve.Flow Rates: Up to 10,800 gallons per day (40,878 lpd)