Why is only one tap losing hot water?
A single tap losing hot water while other fixtures work normally is usually caused by a faulty anti-scald cartridge, a blocked cartridge valve, or an internal obstruction in that specific faucet. This restricts the hot water supply line, preventing you from getting a full, continuous flow of hot water from that specific fixture.
What the numbers show
Counted from the threads quoted below. How we count
- This comes up 17.6× more often in r/Plumbing than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Cleaning or replacing the mixer valve cartridgeDid this help you?
- 2Testing the hot water line by removing the mixer valve and turning the water back onDid this help you?
- 3Checking temperature at other faucets like the kitchen after the tub goes cold to test boiler response.Did this help you?
- 4Adjusting the screw on the mixing valveDid this help you?
- 5Adjusting the red piece with the +/- markingsDid this help you?
- 6Taking out the cartridge and flipping it 180 degreesDid this help you?
- 7Calling a professional plumberDid this help you?
- 8Restarting the unitDid this help you?
- 9Turning off the gas supplyDid this help you?
- 10Replacing the shower cartridgeDid this help you?
- 11Flipping the cartridge upside downDid this help you?
- 12Testing and adjusting the valve shut-off stopsDid this help you?
- 13Flushing out debris from the valve bodyDid this help you?
- 14Trying to trace the pipe inside the buildingDid this help you?
- 15Contacting the building superintendent or maintenance for assistanceDid this help you?
- 16turn off the shower head, run the faucet, and let it get hot again before turning the shower head back onDid this help you?
- 17Check if the shutoff valve under the sink is seized closed or the line is blockedDid this help you?
- 18Check if the handle is installed backwardsDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“After moving in I discovered the shower has no hot water. It runs cold at at the same high pressure when set to hot and cold.”source ↗
“I replaced the cartridge with the same model, had the same results.”source ↗
“I cant find hot water anywhere in the rotation of the handle.”source ↗
“My basement shower never gets hot despite having hot water piping.”source ↗
“Sink in the bathroom does get hot water to it, as well as every other faucet and shower in my home.”source ↗
“The hot water finally stoped coming out 2 days ago, but it was working/not working intermittently for about a week.”source ↗
“Its just this one hot side of the tap that's the issue.”source ↗
“EXCEPT for the tub. The tub and shower do not share fixtures. For some reason, I can only get about a gallon of hot water before it drops to lukewarm when I try to fill the tub.”source ↗
“There is a pipe outside my apartment building which was expelling water at a high pressure (I came home to it and it slightly leaked into the basement)”source ↗
“I don't know how long it was running, but 7ish hours later, there is no hot water in my unit at all.”source ↗
“While trying to trace it out, I cannot quite find inside where it goes. There is another basement access in the building, but that's locked off to the tenants.”source ↗
“whenever I turn on the shower head, any hot water will gradually disappear in less than 45 seconds.”source ↗
“less than a minute of hot water has been killing me especially with other issues going on having moved in.”source ↗
“The problem is when I turn on the hot water tap only I get nothing but cold water.”source ↗
“Even if I let it run 10 minutes If I turn the tap on, shut off the cold water supply line all the way, hot water supply wide open still no hot water on the hot side of the sink.”source ↗
Where this came up
People with this problem also raised
- 3Why does my hot water stop when the sprinklers run?
- 8Low hot water pressure at only one faucet
- 12Why is there no water pressure after changing a faucet?
- 3Why are all my faucets sputtering on hot and cold water?
- 3Kitchen faucet sprayer leaks only when turned on
- 3Why are my cold taps running tepid after a water heater service?