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Question DetailsAsked on 9/27/2016

I can hear running water inside my hot water tank. Meter is running on the outside. No visible leak in the house

I can hear the water running at each toilet, tub, shower, and washer. Turning the hot water off at the devices that use it, the noise is still there. When I turn off the cold water inlet to the tank the sound goes away and the outside meter quits running. Cold water inlet is cold and the outgoing pipe is hot. Cannot find any visible water leak anywhere in the house

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1 Answer


Depends - you said you shut off the cold water inlet at the tank and it stopped sound and meter running.

1) about your water shutoff on the incoming water line - IF the pipe from the shutoff valve which you closed goes both to the hot water heater AND has a branch off to the rest of the house "after" the valve, then you shut off the whole house when you closed the valve so the problem could be anywhere in the house in the COLD system - would have to wander around with ear to wall or with stethoscope (metal headed ones work better - about $10-15 at pharmacy department - or use paper towel or wrapping paper cardboard tube) listening at pipes and walls to hear where it is leaking loudest. Also listen at sewer pipe where it goes into ground/slab - to hear if there is running water there. IF so, then pretty much has to be going through a faucet or toilet or such to get into the sewer lines. Also check any floor drains to see if water is running into them from the walls, and check all around the foundation for signs of leakage.

IF shutoff valve was right above water heater and the line from it goes only to water heater, check out items in 2) below first as more likely.

Common cold water leak points if you don't have visible flooding by now:

a) frozen hose or hose faucet (if below freezing in your area already) which broke due to freezing and is dumping water outside (from hose) or maybe in wall (from broken faucet / pipe)

b) broken (including from freezing) or stuck-on irrigation/sprinkler system

c) leak at spa/hot tub/pool if you have one

d) broken/leaking pipe in basement or crawlspace where it is not normally visible

e) water treatment system with stuck backflush valve so it is continually backflushing the water softener/filter system down the drain

f) well recirculation system running continuously. Some well systems have a return pipe from the house to the well to trickle circulate the water in the line from the well continuously to prevent freezing - some are manually turned on or off seasonally, some run on a timer which might be stuck on

g) kids playing in the mud or washing bike or such left hose or faucet on

h) feed line or dehumidifier leaking - either on furnace, or stand-alone with permanent water piping to it, if you have either


2) if your water shutoff is right above the water heater and on a pipe that leads ONLY to the water heater, then the leak might be:

a) on a hot water pipe elsewhere in the house - check under cabinets, on any levels below bathrooms and kitchen, in basement and crawlspace - also check carefully any water-using device that sits right over a floor drain like a washing machine or water treatment system - could be leaking right down into drain so not visible

b) leak in a hydronic (hot water) heating system IF the water heater provides the hot water for that system as well as domestic hot water - could be baseboard or in-floor radiant heating

c) check the areas around base of water heater for leakage, and also the outlet of the overpressure/overtemp valve coming out of the side of the tank near the top - sometimes that is (illegally) run into a drain with regular piping or with a rubber hose so if that valve is "popping off" and releasing water (properly or because it is getting old and leaky) it might be running right down a drain that you don't see.

d) running toilet AND getting only hot water from a stuck tempering valve (which usually mixes hot and cold) so it is running only hot water to toilet tank - but would have to be a pretty substantial leak, though if getting only hot water I could see the outlet float seal going bad pretty fast in full-hot water. Would expect to see a pretty visible agitation in the toilet bowl if running enough to hear throughout the house

e) if you have a sauna with automatic hot water feed to the sauna either for a mist/fogging system or to the steam generator (some use hot rather than cold water to heat to steam faster), check if continuously flowing or leaking - ditto if you have a hot tub or such which used hot water feed

f) pool leak, if your pool draws hot water from your water heater - pretty rare, but some people set up above-ground pools that way with an oversized water heater, especially in warm climates where not much pool heating is needed

g) if none of these, back to 1) above and the stethoscope


When you get it fixed, contact water company - sometimes they will credit back at least some of the usage charges over what you normally use. Some will take your word on it, some require a written invoice from a plumber stating what the leakage source was and that they have fixed it - and some say they are sorry but you used the water and have to pay for it.

Answered 3 years ago by LCD

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