My shower valve leaks. It started leaking a couple of weeks ago and I replaced the cartridge. I had to re-use some of the old parts because the new ones wouldn't fit. The valve stopped leaking for a while but it now leaks again, just like it did before.
Two or three months ago my water heater started leaking just a bit. I was going out of town, thought it was just that the water heater was old, and replaced it. Then I checked and it was only 8 years old, making me think that age was not the issue.
I'm thinking the two problems are related. I think either my water pressure from the city is too high, and I need to put in a pressure regulator. (I haven't checked it yet but plan to later today -- it's 2:00 am now.) Or I need to put in an expansion tank to take some pressure off as the hot water causes the pressure in the pipes to rise.
Am I right in my thinking that one of those two problems caused the water heater to fail prematurely and now is causing the shower valve to leak? If so, I suspect both those jobs are beyond my capabilities, and I'll need to call in a professional. And to do it as soon as possible, before a pipe springs a leak somewhere beyond just at the shower valve.
Anything more than checking water pressure from the city that I can do to isolate the issue?
UPDATE: I bought a water pressure gauge and tested it. During the day it was about 110 psi. During the night it apparently peaked at 140 psi.
The fix thus seems to be to put in a pressure regulator and/or an expansion tank. I've looked into that and I doubt I can do it myself. Looks like I'll have to hire a plumber.
UPDATE 2: I talked to a guy from the city. He said they have made no changes to the water pressure in my neighborhood. Since we are at the bottom of the hill our water pressure has always been at about 110 psi for the 30 years we have lived here. He said it shouldn't be a problem unless we don't like the high pressure. He also said that there is no backflow preventer between our house and the water main.
I also talked to a plumber. He seemed happy to put in a pressure reducing valve if we want one. (No surprise there.) He also said that if we put in a pressure reducing valve we should also put in an expansion tank.
But I was surprised that he was not that concerned about the high water pressure. Maybe the leak in the water heater and the leak in the shower are just unrelated problems that happened coincidentally rather than as a result of high water pressure, as was suggested in the first comment here.
I'll think about it some more.