Reverse osmosis water filter continuously runs water down the drain when the pump is in both running and off mode?

Reverse osmosis water filter continuously runs water down the drain when the pump is in both runing and off mode?

This question is best answered by documentation from the manufacturer, but let's guess at some possibilities.

There might be a malfunction. Has it always done this or just started doing it?

When the pump is off, that is, not actively producing purified water, there is no need to continually run water to drain. The unit might automatically "self-cleaning" at regular intervals when off for long periods. Is this feature defective?

These units typically waste 4 to 5 gallons for every one purified, unless you have a zero waste unit. You might want to find a way to recycle that waste for other uses.

Are you sure the water is going to drain? Zero waste units recycle the waste back into the water supply.

Actually, this problem start when the High pressure automatic switch get damage, I change the swithch and the unit was working proberly, but I observe that the filter continuously runs water down the drain,
- I install the filter since 4 years,
The unit is in normal use and not off for long time,
- could this happen because of the damage of the membrance?

What is the brand and model of your unit? I don't think changing the switch would damage the membrane. Four years sounds like you are ready for replacement, but if it was working OK before you changed the switch, it would be quite a coincidence for the two issues to be unrelated. Where is the drain water coming from, the purified water or the waste stream? The purified water just has a valve that turns off when not needed, doesn't it?

Dear Chic,
Thank you for your replay,
Actually the water coming from the waste stream,