RO minimum operating pressure

[Heimhenge]

Fellow Appliantologists,

We've had continuing issues with our under-the-sink RO system. Mainly stuck valves and wasted water. Last plumber to look at it said that maybe we didn't have enough water pressure for it to function properly. Not sure what that has to do with sticking valves. We're on a well and use a jet pump to pressurize our home system. With the current pump settings, it kicks in when the pressure drops to 30 psi, and kicks off when it hits 48 psi. I know that's lower than city pressures, but from what I could find online that's enough pressure for an RO system to work. Especially since we have a softener upstream so the RO gets fed very low TDS water.

For what it's worth, the RO is a "Reversed Osmosis Drinking Water Systems" Model GRO-5-Stage. A little over one year old. Connected via a real tee and not one of those self-piercing hacks. It should be using 1 g to produce 1 g ... important for us with our well. It's drying up like most in Arizona.

So is the house pressure an issue, or did I just get a bad unit with cheap valves. Replaced them twice now. Thanks!

[Slav]

I think you were misinformed about 1 to 1 ratio on your system. Even the official website PENTAIR states " For each gallon of water produced, several gallons are discharged as reject water". As the bladder stretches inside the storage tank when it's getting almost full, the ratio goes up to about 1 to 10 gallons of clean to wasted water.

That being said, the minimum pressure for RO systems is about 40 psi. So you are just about on the edge of minimum requirements. Low TDS water going into RO system is not as important as the pressure. Because you need a lot of pressure to "push" the water through plastic-like membrane. Also, if it's been a year, you need to change those filters... you didn't mentioned if you already changed them.

RO system is great at reducing Fluoride in the "city water", but if you are on a "well water," maybe a simple carbon block or two filter is sufficient for your needs with NO waste water.

Edited August 21, 2019 by Slav