Method and system to flush an RO system

1. A system comprising:

a membrane module having; an inlet connected to a feed line, the membrane module having a concentrate outlet coupled to a concentrate line, and the membrane module having a permeate outlet coupled to a permeate line, the permeate line communicating with a faucet; and

a flush reservoir communicatively coupled between the permeate line and the feed line;

wherein the system is configured such that permeate does not enter the flush reservoir while the faucet is turned on, and permeate does not enter the flush reservoir until after the faucet is turned off, when a portion of permeate is delivered to the reservoir and then delivered to the inlet of the module to flush the module;

an automatic shut-off valve coupled between the permeate line and the feed line and operative to open and close the feed line;

a first check valve between the permeate line and flush reservoir; and

a second check valve between the flush reservoir and the feed line, wherein the automatic shut-off valve closes in response to a build-up of pressure differential across the shut-off valve, the check valve between the permeate line and the flush reservoir opens in response to a pressure buildup in the permeate line, and the check valve between the reservoir and the feed line opens in response to a reservoir pressure being greater than the feed line pressure.

2. The system of claim 1 , wherein the reservoir has a volume of about 1 liter or less.

3. The system of claim 1 , wherein the feed inlet delivers feed water to the module at about 75 psi or less.

4. The system of claim 1 , wherein the automatic shut-off valve is a non-electric automatic shut-off valve.

5. The system of claim 1 , wherein the feed line delivers water from a feed source at home water pressure conditions.