I have an APEC Water RO system that has recently stopped working properly (low flow caused by inadequate water in the tank). The system is ~14 months old, and I just recently changed the stage 1-3 filters. It appears that water is getting stuck in the stage 4 membrane and not making it to the tank and/or faucet. Here's what I've done to troubleshoot:

  • Removed stage 1-3 filters and reinstalled them
  • Drained tank and checked pressure while empty (7psi)
  • Removed each quick connect fitting starting from the water line throughout the system, checking to see if water was flowing. Identified the exit line of the stage 4 membrane as where the water flow stopped
  • Opened the stage 4 membrane (first time I've done so) to look for obvious issues -- but I have no idea what to look for and nothing seemed wrong

Any ideas on what might be causing this?

  • Probably membrane replacement time. Are you maintaining the stage 1-3 filters correctly? Usually when membranes fail they leak instead of get plugged up, but improper filter Maint in stage 1-3 could simply plug the membrane. Water needs to be pre-filtered to near clean before the membrane. Accidentally washing containments from stage 1-3 filter during cleaning was probably what happened. – Tyson Aug 29 '17 at 19:00
  • Any idea to know if the membrane is bad? I tried to remove it and it wouldn't really budge, not sure if water should be able to flow around it like the stage 1-3 filters? As far as maintaining them, I think so-- only changed them once in the 14 months but they were in the right order. I did notice the sediments filter wasn't "seated" properly when I removed and reinstalled during troubleshooting. – Matt Aug 29 '17 at 19:19

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