Q: I have a shower in my master bath that has had low pressure since we built the home five years ago. I’ve taken the head off and the pressure is still weak. All the other water sources in the house have very good pressure. A friend mentioned that the cartridge could be the culprit. Does that sound right? Is it hard to replace? I’m pretty handy and have fixed a bunch of stuff in previous homes.
A: If you have good pressure everywhere else, then I would agree with your friend that the cartridge is probably the problem. Since it’s been doing this since the house was new, it probably has a small piece of dirt, solder or other debris in it. Changing the cartridge is not difficult, although the exact procedure will vary between faucets and manufacturers.
First, shut off the water supply. Since it’s unlikely that you would have individual shutoffs for the shower alone, you’ll need to shut off the main supply to the entire house.
To remove the old cartridge, pop the plastic cap off the center of the handle to access the screw underneath. Remove the screw, and remove the handle. Behind that is a trim plate — remove the screws and remove the plate. That should give you access to the cartridge, with will be held in place with screws or a threaded ring.
Take the old cartridge to any retailer of plumbing supplies, and they can fix you up with a new one. Complete reinstallation instructions will be included with the new unit. Incidentally, you can also buy repair parts to rebuild the existing cartridge, but I would recommend spending a little extra and simply replacing the entire cartridge unit.
Before installing the new cartridge, I would recommend flushing the valve to be sure you’ve removed all the debris inside. With the cartridge still out, have someone slowly turn the water back on. Don’t turn it all the way back on, because that will generate quite a stream. Watch the water as it comes back on, and you should see a strong, steady flow begin. Assuming it does, have your helper shut the water right back off again, then proceed with the cartridge replacement.
If the cartridge replacement doesn’t fix the problem, then you could have some type of obstruction in the water lines leading to the shower. In that case, I would recommend having a good plumber come and take a look — if possible, use the same person who plumbed the house originally, since they’ll know right where to look.