Our kitchen floor is very warm. We don't have in-floor heating and we hear the quiet hiss of running water all the time. My fear is that a pipe has ruptured under the house and is slowly leaking hot water. The foundation around the kitchen is dry, however, and there is no indication of a leak anywhere in the house.

Location is the Phoenix area of Arizona, USA.

What could this be?

  • 1
    One look at your water meter should tell you if you have a water leak. There is a flow indicator (star or triangle) which will be seen turning. If it is a hot water leak, then turning off the cold water supply to the hot water heater should stop the leak? Do you have a tank or a tankless water heater? Feb 24, 2018 at 2:30
  • I agree with jim. I have used an automotive stethoscope and a simple piece of pipe/ conduit to find leaks and pipes in the past. On a slab with a broken pipe some times you can hear small rocks bouncing around the jet from a pinhole leak. With below the slab water pipes the heat from the hot water in the pipes radiates up. The kitchen is usually closer to the waterheater on all of this era homes I have worked on so the bathroom kitchen hot water use can make the floor warmer. If your water ussage and power bill are significantly different from a similar home maybe, if a leak OUCH$
    – Ed Beal
    Feb 24, 2018 at 2:54
  • i am curious. why did you not think to turn off the water to the house just to see if the sound of running water would stop?
    – jsotola
    Feb 24, 2018 at 6:13
  • 1
    I did. It stopped. Apparently the hot water pipe has a leak.
    – acpilot
    Feb 24, 2018 at 6:14

2 Answers 2


If the floor is warm and you hear a hiss, it's not "slowly" leaking, it's spraying in a significant quantity. Prepare for a large utility bill, and go shut off your water supply. It takes a pretty significant leak to noticeably warm the floor, in my (unfortunate, and that was a BIG gas bill) experience.


Do you have forced hot water heat? If so, the leak could be in the heating system, not in the drinking water pipes. Try turning off the water to the hot water heater and see if the hiss stops.

  • I did and it stopped.
    – acpilot
    Feb 25, 2018 at 16:59
  • So now you know it is the hot water, not the heating system. Hope you ind the leak soon and can fix it without that much bother.
    – Yehuda_NYC
    Feb 25, 2018 at 18:29

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