I have a shower stall in a guest bathroom that is used very infrequently (about once per year). The water pressure is perfect in the sink and toilet. But, we cannot get decent pressure in the stall shower. I've had three different plumbers work on the problem. They have installed a new cartridge assembly (Delta).

One plumber used air to blow out the pipes thinking that something could be blocking the flow of water.

They have removed the flow restrictor from the fixture.

Nothing has worked. The water just trickles out.

Please help. Thank you.

Hi Sally

The first thing to check here will be to have the cartridge entirely removed from the shower valve, OK? First, shut the water main off. Next, drain the pressure off at the shower valve. The next step is to tuck a towel up and around the valve and the hole in the wall. Then, pull the cartridge and all the guts to the valve, and pull the curtain or shower door closed and have someone turn the water main back on. Now, observe the water pressure coming out of the valve. Is it a trickle now or is the pressure and volume GREAT? You may want to do this again, only isolate the hot water flow and the cold water flow so you can be sure they are of equal volume/pressure. With todays shower valves, if you have low water pressure in even just one pipe (hot or cold), you'll get the same low pressure from the other pipe (pressure balanced shower valves).

If the water is trickling out then the issue could be at a shut off valve that may be hidden in the wall just below the shower valve (usually find an access panel on back side of shower, but if not one, one may need to be cut in to check this) or it could be the pipes.

If there is a DIVERTER (low/high flow) involved with this valve, you may find that the diverter is not capable of fully diverting the water or is defective in terms of the hole placement in the diverter or valve. I have seen it where the diverter was replaced and it was a MIRACLE!!

That's where I would start anyway...

Mark