Reverse Osmosis waste water expected flow

[Smodderman]

Good day, I have been trying to troubleshoot my RO system. I had an under the sink PUR RO system for about 3 months until it stopped producing water. the waste water runs all day and night yet nothing ends up in the tank. I tried replacing the RO membrane (High TDS water, maybe it failed early) but that did not help. I measured my drain flow (Rated for 300 ml/min) and it came out at roughly 150ml/minute so I suspect I need a new flow restrictor, however for the fun of it I also tested my drain flow without the flow restrictor as I expected a high flow of water similar to the input flow (40-50 psi on well water) but I only got 600ml/minute. Should I be getting a better flow before the flow restrictor?

Sunk cost fallacy has me considering if its even worth buying replacement parts or if I should just buy a new system thats the same and use the old system as replacements? (New system is only $300 with the filters) I just don't want the new one to fail in 3 months time again.

Edit: New system is now only $200

 

[Bannerman]

The drain flow rate will vary depending on the type and GPD rating of the membrane as well as the type of flow restrictor utilized.

For example, a highly efficient 50 GPD Pentair GRO membrane will typically utilize a150 mL/min capillary drain restrictor whereas a conventional 50 GPD membrane will often utilize a 350 - 500 mL/min capillary or spiral restrictor, or a 200 - 275 mL/min inline restrictor.

A conventional RO system ASV (auto shutoff valve) will turn off production once the storage tank pressure has risen to 60% of the feed water pressure. Since it seems RO water (permeate) is not entering your system's storage tank, the ASV is not being satisfied so water continues to flow to drain. It seems there maybe a blockage somewhere between the membrane housing's permeate connection and the storage tank which is not permitting flow to the storage tank.

 

[Sponsor]

 

[ditttohead]

You can get RO's for <$200, but considering the extremely high liability and the potential for leaks, please do not get the cheapest piece of junk you can find. Be sure it is from a real company so if it does cause $100k of water damage... you have a shot at some help on the insurance claim.

 

[Smodderman]

You can get RO's for <$200, but considering the extremely high liability and the potential for leaks, please do not get the cheapest piece of junk you can find. Be sure it is from a real company so if it does cause $100k of water damage... you have a shot at some help on the insurance claim.

That's a good point. the connections are solid (better then the rainfresh systems I have seen around here) so I'm not too concerned on leaks, but the operation may be less performant then other systems.