A reverse osmosis liquid filtering assembly includes a reverse osmosis membrane for receiving intake liquid and creating permeate and concentrate liquid and a tank having a first chamber for storing the permeate and a second chamber for receiving the concentrate liquid, the first and second chambers being operatively connected so that the concentrate liquid in the second chamber pressurizes the permeate in the first chamber. The embodiment may further include means for directing the concentrate liquid into the second chamber, wherein the means selectively directs the concentrate liquid into the second chamber only when the faucet is open. To relieve backpressure, a connection between the second chamber and drain may be provided.