RO filtration cleans water by taking out the totally dissolved solids (TDS) which contaminate the water. RO membrane removes an average of 95% of dissolved contaminants. RO works by using pressure to force the water solution through membrane, retaining the TDS on one side and allowing the pure water to pass to the other side. TANKLESS-400 RO BP is a system featuring on-demand, continuous-flow water production. With NO storage tank to fill, the reverse osmosis unit does not run until RO water is needed. TANKLESS-400 RO BP low-energy membrane to purify between 400 ±20% gallons of water per day, depending on your water conditions. Options: Backwash Alcalaine Minerals Silver post filter Magnet Double handle faucet