PLEASE HELP!!! My plumber replaced both GP77759 and GP500520 Kohler shower cartridges and now the water flow rate in the showers is very low. The flow rate was excellent prior to him simply replacing the cartridges with brand new ones. Plumber has no clue how to fix it. Flow is completely fine in the rest of the house and remains unchanged. ONLY in the two valves where he replaced the cartridges is the flow reduced from previously. I desperately need this fixed!! No one at the company has a clue either. Please help!

  • Hello, and welcome to Stack Exchange. What was wrong with the two showers before the plumber got to work? – Daniel Griscom Nov 11 '18 at 11:52
  • Some of these shower valves have two small shut-off valves operated by a screw driver (allows changing cartridges without shutting off water elsewhere). Does your shower valve have those? Did the plumber shut those to change the cartridges and fail to reopen them fully? – Jim Stewart Nov 11 '18 at 12:08
  • The temperature wasn’t getting as hot as usual, and only in those faucets. I knew it was time for new cartridges as when this happened about seven years ago, I got the cartridges replaced and good as new. This time, made it much worse. – user92965 Nov 11 '18 at 12:32
  • I don’t know if my shower valves have the two small shut-off valves, but I did need to turn the main water off while he replaced them. I also don’t know he if he reopened them fully- is there a way I could check myself? Plumber claims he did everything as he should and settings were exactly same as the old cartridges he took out. (Clearly not, since pressure is way off and temperature still isn’t fixed.) – user92965 Nov 11 '18 at 12:35
  • 4
    Possible duplicate of Low water pressure after new shower cartridges installed – Kris Nov 11 '18 at 17:35

Remove the shower head and see if you get good flow.

Sometimes the work on the pipes dislodges crud and it clogs filters and outlet valves.

If the flow without the shower head is good, clean the screens and the holes in the head. If the flow without the shower head is still poor, have the plumber check for clogging in the cartridges and replace them if needed.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.