Hi all,

I have a 40/40 producing 34 tds from 300 tds tap water, with a large booster pump before it. The water pressure is about 25psi before the pump and about 75 psi going into the RO.

My question is about the flow restrictor valve which is on the waste outlet of the RO.  I was under the impression that the valve needs to be half closed (or so) to maintain the pressure in the RO so it forces water through the membrane, except when flushing the system, when the valve should be wide open, releasing the pressure and not creating any pure water..

In my system, if the valve is turned fully open, I still produce pure water almost as quickly as it was before. And the TDS doesn't seem to alter dramatically.

I've checked the valve, it definitely works, and the pressure definitely goes up if the valve is closed.

What have I got wrong o troubleshooting gurus?

Thanks for the reply AM, but mine's not a screw valve, just an inline quarter twist valve..  But I hear what you're saying about liking a lot of pressure, I'll certainly try it again with much less waste..  (currently I'm running about 50/50 waste pure, so that could be my mistake..)

The question still stands though, if you turn the waste fully open, (to flush the system), does your RO still produce pure? And at a similar rate?