Tapping sound behind walls when sink/toilet running - could this be something aside from a leak?

Submitted by Widespread_Looting t3_11upiwz in DIY

I hear a tapping sound in the wall near two bathrooms and am trying to figure out what it is without opening the drywall to explore. Moved into this house about 8 months ago and am still learning it's quirks. House was built in 2001 so plumbing is modern.

  1. after flushing one of my toilets, while the tank is filling there's a tapping sound directly behind the tank in the wall. It continues for about 10 seconds after the tank is full, then stops. No signs of water anywhere including in the ceiling of the room below.

  2. similarly, while the sink is running in a different bathroom, i hear a tapping sound in the ceiling of the room below, which stops when the sink stops. Also, no signs of water anywhere in the drywall or ceiling below.

I know next to nothing about plumbing so am really after a recommendation about whether I should call on a pro to investigate or if this is some sort of normal water pipe expansion, etc.

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Comments

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jackson71 t1_jcp88ut wrote

Sounds like expansion and contraction due to temp differential.

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SlideConsistent t1_jcp5maj wrote

It's probably just the water pipes rattling around in the wall. I know that my water pipes rattle around because I can see them on the floor joists in my basement.

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TheRageDragon t1_jcpajxz wrote

Yep, ours have been doing the same thing for over a decade. It's like whale and ocean sounds to me now. I'd be worried if it stopped at this point lol

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[deleted] t1_jcp83i2 wrote

[removed]

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gredr t1_jcp9sqa wrote

I am imagining a poor copper pipe, alone in the wall, trembling and sweating from the massive effort of filling a giant toilet tank all by themselves.

In reality, though, pipes don't "vibrate from the struggle." Indeed, pipes don't "struggle" at all. In this case, I'd put a few bucks down on the "thermal expansion" theory.

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stereoroid t1_jcp5mxx wrote

Could it be some odd “water hammer” situation? If anything might need bleeding, doing that might improve matters.

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fluffybottom t1_jcp74or wrote

  1. When pipes run hot water they sometimes make clicking or knocking noise as they expand.

  2. It’s possible you have flexible pvc pipes that can move a little when the water pressure increases or decreases.

  3. Any of the things already listed.

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cnyle111 t1_jcpam2a wrote

When the lines were ran during construction the holes that were drilled through the wood were too tight. As the pipe expands and contracts you will get a ticking noise that sounds exactly like a drip. As the seasons change and the humidity of the house changes the sound can come and go.

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Widespread_Looting OP t1_jcpf13t wrote

Thanks for all the input, I'm relieved nobody said "oh yeah, that's a leak." This is our first winter in the house so I'll be interested to see how the temp and humidity changes affect the sound. I don't recall hearing anything last summer but can't really say I was listening either.

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sensitive_kitten t1_jcpwldv wrote

If it was a leak it wouldn't only be heard when the water is moving truth the pipes. It would be constant. Most leaks aren't audible either, that's why they can be so destructive.

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OnTheClockShits t1_jcq8psv wrote

I too am relieved nobody said it's a leak because our house that we moved into like 3 years ago has a very similar tapping noise, happens when we shower and sometimes with our sinks. I haven't seen any water damage in all this time, so was hoping it was just thermal expansion. Definitely not water hammer, that's pretty distinctive sounding and really only happens right when the water is turned on.

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markmevans t1_jcq4yme wrote

If your house was built in 2001, I suspect it has PEX pipes, not copper as others speculated. In the end it’s the same issue, thermal expansion or vibration from pressure changes.

Check out this video: https://youtu.be/Xy9aJdX5xF0

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duderanchjuvenilia t1_jcp6xrh wrote

It could be pipes rattling from poor pressure as it tries to pump water into the toilet tank. Could be that someone closed the valve at the wall so water is struggling to get through. Have you tries opening the valve under the toilet a little?

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GearsAndSuch t1_jcp709j wrote

Could be a vibrating pipe or a in wall air valve.

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windy496 t1_jcpehcm wrote

I have that when I run the sink taps in the 2 piece bathroom off the master bedroom. It is the pipes contracting and rubbing on a 2x4 in the wall. When I push on the wall it stops for a short time and starts up again until the pipe warms up.

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skydiver1958 t1_jcq2qk7 wrote

Thermal expansion/ contraction. Same thing in my house. Hard to fix without opening walls as a rule. Not uncommon in production builds. Nothing to worry about.

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PolarBear1972 t1_jcrp597 wrote

We had the same problem, water pressure too low and replaced our pressure tank and all is good

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monotakes2 t1_jcpqokl wrote

It's grandma living in the walls.

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