Fix Low Water Pressure in Just One Bathroom
LESLIE: Even in the middle of home improvement projects, we’ll take your call. Linwood just got off the lawn mower to talk with us. How can we help?
LINWOOD: Oh, yes. I have a two-story home with adequate water pressure on the bottom floor and the shower unit and tub unit combo upstairs, when I go to put the hot water on, the pressure drops dramatically.
TOM: How old is your house, Linwood?
LINWOOD: It was built in ’81.
TOM: Ooh, that’s not that old.
LESLIE: And how about the other fixtures upstairs? Everything runs OK?
LINWOOD: Yeah, the faucet upstairs runs relatively well.
TOM: But it’s everything that’s feeding that one particular bathroom.
LINWOOD: Yes. As far as I know, yes.
TOM: Have you identified a supply valve to the plumbing in that part of the house that could possibly be partially closed even if it appears to be open?
LINWOOD: I haven’t, no. I do have a water filtration system, down in my cellar, that has been disconnected. And by what I can see, everything’s being bypassed.
TOM: Is it just the shower or is it everything in there?
LINWOOD: The tub and the shower only. The faucet, relatively, has decent water pressure.
TOM: Because I’m wondering, also, if you eliminated the possibility of a water restrictor in the showerhead.
LINWOOD: Yep, I actually removed that when I first bought the house.
LESLIE: Don’t tell everybody.
TOM: (chuckling) Yeah, a man after my own heart. I do the same thing myself.
LESLIE: (chuckling) Me, too. I’m always like, “Can I remove that low flow? OK, great, I’ll take it.”
TOM: “OK, so that’s out. Because I want to pay for that water at a recreational budget.”
LESLIE: (chuckling) Exactly.
TOM: Linwood, if you have just one fixture like that, that’s performing poorly and everything else works pretty well, most likely the cause of that is a valve somewhere on the way that’s partially closed. Sometimes, if you have supply valves to different bathrooms and different parts of the house, even if the valve is sort of backed off all the way and seems to be open all the way, it could be partially closed. Generally, the bathroom that’s the farthest away from the main is going to be the one that has the least pressure. But in a 1981 house that’s rarely the case because you have copper plumbing throughout the whole thing. So I think you need to get to the bottom of where these fixtures are restricted and I suspect that it’s in a valve somewhere between the main supply and this upstairs bath.
LINWOOD: Now, the one thing I was wondering is I have a Simmons Model A control valve. It’s a single knob that controls both the hot and cold water.
LINWOOD: And I was wondering if the little rubber gasket that controls the ports that are open in the knob, if those could have been clogged over the years.
TOM: Quite possibly. It could be. Or it could just be a bad valve altogether. That’s not a bad idea and a good place to start. But it’s – you’re on the right track here, Linwood. You’ve got a problem with a valve somewhere that’s stopping the water from getting to that. You took the showerhead out of the equation by removing the water restrictor. So now, it could possibly be the diverter valve. And if you’re going to replace that diverter valve, look for one that’s pressure balanced. Because a pressure balanced valve will stop you from getting scalded if somebody else opens up the hot or cold water tap somewhere else in the house.
LESLIE: Or flushes the toilet.
TOM: Yeah, exactly.
LESLIE: Now, get back to mowing.
TOM: Linwood, thanks so much for calling us at 1-888-MONEY-PIT.