Hot Topics: Sounds Like Water Running

three sets of white PVC pipes against a gray wall

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motherOFaCUTIE - Member

I REALLY need to know what this problem is. For about a month now, we can hear what sounds like water running/hissing through the hot water pipe to the bathroom, right behind the hot water knob in the tub to be exact. We can get to the pipes behind there and that is where the sound is the worst, pretty loud. But no sign of leaking water.

It's constant, never stopping, and has gotten a little louder recently. You can hear water running through a pipe in a crawlspace under that part of the house. No wetness there or in the basement where the pipes are. Just replaced hot water heater and the problem is still there. If you turn off the hot water valve at the top of the hot water heater, the sound stops. Also, turning off the main water valve in the basement stops the sound.

The plumber said to wait and see what our next water bill is like to see if it is higher, since he couldn't figure out the issue.

Please help me figure out what the problem is. Thank you

Norm201 - Member

Turning off the cold water supply to the HW tank stops it? As does turning off the water main to the whole house. It means water is in fact moving through pipes. Are there any constant hot water demands being used? Dishwasher, hot tub, any appliance that would need hot water? Do you have isolation valves that might turn off sections of the house? For instance hot and cold water to the 2nd floor?

Or perhaps just the kitcken area or just the bathroom area. Are any outside hose bibs leaking? It might sound like hot water but it could be cold water supply. Does turning on any hot water (or any valve) stop or change the noise? How about turning off the isolation valves under each sink? See if you can find one item that stops it.

motherOFaCUTIE - Thread Starter

Turning the hot water supply off at the tank stops it. We've tried valves to different areas of the house. Nothing happens. We followed the line where the sound is coming from and it leads to the hot water faucet in the bathtub. That is where it is the loudest. But like I said in my earlier post, we can get to the pipes behind the wall, where they connect to the knob and no signs of water.

Norm201 - Member

If in fact that is the location then you may have a leak and its traveling by following a pipe or some other structural member. I don't mean to scare you but you really need to isolate it and fix it. Sooner or later you will see water damage of some sort some place. Can you open up the wall behind the tub? Make an access panel?

Another thought...does the tub faucet or shower head drip or leak? If so then its a minor problem of just replacing washers or cartridges.

Another thought...Are you sure its running water/ Maybe it could be vibration from something touching the pipes.

Pulpo - Member

How many bathrooms are there? How many floors are there? Is the crawl space only accessible from the outside? It seems strange that a hot water pipe would be in a outside crawl space, in Ohio. Since you are dealing with hot water, put on a pair of gloves & touch the pipe in various places. You should feel a vibration as well as hear the noise. Try to determine where the vibration is the strongest. What brand is the hot water heater?

motherOFaCUTIE - Thread Starter

There is an access panel to the tub. No sign of water anywhere. But that is where we can hear the sound the loudest. Turning off the cold water valve on the hot water heater also stops the noise.

motherOFaCUTIE - Thread Starter

The trickling sound in the crawlspace could be from a drain. Not sure. The hot water heater is a Whirlpool just put in today. Sound has been going on for a month though. The hot water pipe that is making the noise stays cool behind the tub when it hasn't been used. So it's not like the water is actually leaking or going somewhere. The water heater doesn't constantly run or anything, so it's not like we are losing anything. Just wonder what is causing the sound. Could it be a seal or elbow joint in the copper pipe?

Pulpo - Member

If water is moving it's going somewhere unless you have a return loop on the water heater, itself. Is the meter turning more than you might expect? Yes, it could be an elbow or another joint in the pipe but then you would see water somewhere.

Hal_S - Member

I've got a hypothesis.

First, 2 questions:

#1 do you have hard water? I'll bet you do.That is, does you standing water result in a grey buildup of minerals on vases or et dishes that you refill with water?

#2 Does your water company use well water?

My guess is, hard water scale is keeping a toilet flap from closing.

That is creating a small water draw.

Something is causing that water draw to create a hissing in the tub.

My other guess is that something within the shower hot/cold mixing valve isn't closing totally,

so the small draw is pulling water from the hot water side.

"It's constant, never stopping and has gotten a little louder recently."

Try turning off the valve to the toilet. Does that stop the hissing?

motherOFaCUTIE - Thread Starter

No, sadly it doesn't. I wish it did then at least I would be able to figure this out. I have noticed a drip from the faucet in the tub recently. But only just this week and this has been going on for a month, the sound. Could that be the culprit? Oh, and the water bill hasn't risen.

Pulpo - Member

What brand hot water heater is it & how is it powered? I'm starting to think it's the hot water heater itself & the sound is telescoping, to the other end of the pipe.

lawrosa - Super Moderator

With all water off to the home look at the water meter...

Is the water meter moving?

Are there any areas of the home where pipes are in a slab and not in a craw space?

motherOFaCUTIE - Thread Starter

Well, it's been going on for a month, and we just replaced the water heater thinking it would fix the problem (the water heater was old anyway). It's a Whirlpool. It didn't fix the problem. It's electric.

motherOFaCUTIE - Thread Starter

We don't have a water meter. How can I determine if it's an outside line or one on the inside of our home that could be the problem?

motherOFaCUTIE - Thread Starter

I have noticed a drip recently from the tub faucet and the faucet has always dripped when the hot/cold mixing valve is turned to the shower mode. Do you think this is the problem? Might I add the mixing valve knob is somewhat loose...

lawrosa - Super Moderator

If it stops when you shut the valve to the heater off, then its on the hot side in the home..

No meter? None outside? Or are you on a well?

No areas of a slab floor where pipes may run under???

Pulpo - Member

Are you talking about the mixing valve or the diverter? The knob can probably be tightened. Maybe some pics of the crawl space, the hot water tank & the tub faucet might help. How is the crawl space accessed?

Hal_S - Member

First, if you don't have a meter, and your plumber told you to check the water bill, you may need to investigate a better plumber.

Second, you don't have a meter, then you are likely on a well- which suggests a possible answer.

When you open the spigot in the bathroom shower, do you get a gurgle or a burp of air before the water flows out?

My best guess so far is that the check valve in your well pump may be leaking, or the valve seat in the shower hot water mixer is worn and letting air through.

You are hearing the pressurization and depressurization of the water system.

If the pump check valve is leaking, (or the pressure tank hasn't been filled with air in years) your system will cycle through high water pressure to low water pressure.

If the hot water valve in the shower is worn, full pressure causes a hissing as water moves from the hot water supply through the valve to the tub/shower pipe.

When the well pump shuts off, pressure drops, and water is sucked back from the tub/shower pipe back through the valve into the hot water supply pipe.

Is there a separate shut-off valve for the hot water pipe to the tub?

Close it and see what happens.

motherOFaCUTIE - Thread Starter

We found the problem—leak in elbow joint.

We looked into the crawlspace and this time we saw water running down. We had to cut a hole in the floor of the access area behind the tub to locate it and fix it. But we finally found the problem, no more grasping at straws.

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