Dripping Sound from Inside of Wall/Ceiling When Toilet is Flushed

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newbie386

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Hi. I live in a 6 years old three-story townhouse, and since some time ago I've been hearing water droplet noise from inside a wall and ceiling whenever one of our toilet on the third floor is flushed.

We have two washrooms on third floor and it's only one of the toilet that's causing this. No sound when the other toilet(on the same floor) is flushed. No sound when using shower or sink. But when this toilet is flushed I can hear water dripping sound even when I'm on the first floor. There's at least one other spot(ceiling and maybe inside another wall too) that I hear dripping sound.

There's no appearance of water damage so far. Dripping sound slows down and ends within a minute or so. When I flush it again it starts again but not as loud. Flush again and the sound is even softer. Another flush and I don't really hear it. After some hours I flush it again and I can hear it loud again.

I thought it was the drain pipe damage but I was told it's unlikely, especially flushing the other toilet on the same floor doesn't cause the same. So I'm thinking it must be somewhere around the connection between the toilet and its drainage. I have no experience in installing or detaching toilet. I see the toilet has no silicone applied around the base.

Any advice would be greatly appreciated!
 

Dj2

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Not having a leak (evidence), it's hard to diagnose from in front of a computer, because the drip noise could be a result of any one of many reasons, or could be something other than a drip.
Have a plumber walk with you when the sound returns as a start.
 

Cacher_Chick

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I dont have any trouble hearing water dripping inside of plastic (PVC) drain piping. Some people build using cast iron piping because of the noise issue alone,
 

Reach4

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I would slowly add a cup of water to the toilet after it has flushed and become quiet. Do you hear that same dripping sound?

If so, maybe you could cut down on the refill water that gets added to the bowl during a flush.
 

newbie386

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I tried adding 500ml of water to the bowl and I didn't hear anything. Tried this several times.
Then did the same with 1 liter of water and still no sound. Then 3-4 liter - No sound
Flushed - drip sound everywhere. I hear this more than 1 spot, at least 3 spots, inside wall and ceiling I hear dripping.
Some are pretty loud in couple spots and less so in other spots. Loud one sounds like someone's knocking on wood gently with finger. It's obviously water dripping on wood surface outside of pipe.

Next day I tried pouring bucket full of water into the toilet, about the same amount in the reservoir, and I don't hear any dripping.
Tried this couple times, no sound, so I tried flushing and heard dripping all over inside.

I tried this again couple days later pouring down a bucket full of water once directly into the hole making the water go down fast then also tried pouring around the hole making a whirl causing slow flush. No dripping heard other than the sound of water rushing through the drain pipe. So again I flushed it and I hear dripping from downstairs wall and ceiling all over again.

This is so weird.. Seems like only the flushing is causing this. .
I'm confused.
 
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Jadnashua

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Did you try shutting off the water inlet to the toilet and monitoring the tank water level? It's not uncommon for the flush valve to not always seat perfectly, especially when they get old (they tend to either get soft and deformed, or hard and then won't conform to the seat to make the seal). Having the chain a little too long can cause a link to get caught once in awhile. Having the chain too short can hold it up slightly, allowing it to leak. If your water pressure is excessive, the fill valve may have a harder time sealing, and lets a little bit of water come into the tank, and if that's the case, it can rise enough to then slowly trickle out the overflow, so again, you'd not see a leak, but one could be occurring.

So, when you hear it, lift the tank cover and see where the water level is...if it's draining out the overflow, fix the fill valve.

If you shut the water off and come back say overnight and the water level has dropped, fix the flush valve (often a flapper, but not in all designs).

It's not uncommon immediately after the end of a flush, for there to be a small trickle of water down the drain...in most designs, the bowl is overfilled, and it doesn't always stabilize immediately. Also note that wind or other things draining, can cause the water in the bowl to be moved slightly by the pressure/vacuum in the system, and that can cause the water to rock and overflow the weir in the toilet, dropping a small amount of water down the drain. Do you notice this more on a windy day?
 

Highlander

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If you're still not finding it, here's another scenario - maybe it's filling up the tank that's causing the noise (cold water pipe wedged too tight in hole in a joist/stud and making noise as it changes temperature).

Try shutting off the valve at the toilet, and flush it so the tank is empty. Wait several hours (overnight if you can), then open that shutoff valve (don't flush or anything) and see if you hear the ticking as the tank refills.
 

newbie386

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Thank you for the replies.
I tried shutting the valve and flush few days ago and noticed the sound was gone. And as soon as I opened the valve I heard that dripping sound. The hose that's connected to the tank had a note attached to it saying that it's connected to the sprinkler system and it also had a small pressure reducing valve installed to it(picture uploaded).

Luckily enough, my townhouse complex was on a routine inspection for smoke detector & sprinkler system, and when the guys showed up I told them this issue and let them hear the noise. He listened to it and said this must be the piping tapping against the joist/stud or whatever as the pressure changes when water runs through pipes after flush. He said the sprinkler piping is flexible PVC and this can happen. He wasn't a plumber but apparently his girlfriend had the same issue and he found out it was that.

The noise was not on just one spot but bunch of spots inside wall and ceiling between 2nd and 3rd floor, and I was starting to think this just can't be all leaks. I wasn't seeing any signs of water damage anywhere. And the guy said if they were leaks they would be leaking all the time not just when I flush the toilet making water moving. Sounds like common sense I guess especially when the sprinkler water pressure is 120psi. Besides, some of the tapping sound (which I've been thinking as water drip) was pretty loud and it would only make sense if the droplet was falling from sky high. So I'm pretty convinced now that it's the piping tapping sound.

I still have a few questions though:

1) Is this kind of thing pretty common to happen?

2) Is it ok to just leave it, I mean if the pipes are rattling like that, is there more chance for leaks to develop at some point eventually?

3) Would it be ok(or wiser) to maybe shut and disconnect this hose and connect the tank with the vanity/sink's cold water pipe?

20170128_173948.jpg
 
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Jadnashua

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What part(s) of your piping is at 120psi? Plumbing code does not allow more than 80psi in the home (a sprinkler system could use more, but should be isolated from the house pressure system; i.e., before any pressure reduction). Excessive pressure can cause some weird things to happen, not including blowing out seals, hoses (washing machine or maybe faucet?), aggravating water hammer, and who knows what.
 

Reach4

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This toilet is the only thing in the house that's connected to the sprinkler pipe. I don't know why they made it this way.
http://ccwd.org/wp-content/uploads/2015/05/factsheet-sprinkler1.pdf says
Fire sprinklers can be supplied by a separate water connection, with a toilet connected to the end of sprinkler piping to ensure that the piping is occasionally purged by flushing the toilet to prevent stagnant water. This arrangement is referred to as “passive purge.”​
 

newbie386

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Ah I see. Thank you. Maybe it's not a good idea to connect the tank with sink's water supply then.
I guess I'll just have to live with this noise. I hope the rattling of the piping doesn't eventually create leaks.
 

Reach4

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During the fill, maybe feel that PRV for vibrations.

I don't expect that ticking will damage things. I wonder if a reduced flow would make things better for you.

I wonder if you were to turn the screw on the PRV 1/2 turn CCW (expecting to reduce the pressure and therefore flow, to the toilet, would that reduce the sound? More than 1/2 turn? Keep track of turns so that you could restore it.

You could experiment with having the stop valve partially open during a flush. I think that kind of valve is not made to be run partially open indefinitely, but it should be OK for an experiment. If that helps the noise, maybe a more permanent change could be made.
 

Mdmm55

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Friends, kindly help me advising, as I do have a similar issue. When I flush toilet in bathrooms on second floor, I hear the water dripping sounds under the ceiling while standing on ground floor, below bathroom.
Now if I flush toilet in bathroom on ground floor right below bathroom on second floor, I do hear same dripping sounds at the same spot in roof.
Seems like both bathrooms have a common draininage pipe, causing sounds. Sounds comes from more than one site under.
I do not see any spot on ceiling/roof.
Please suggest any help ?
 

Reach4

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Friends, kindly help me advising, as I do have a similar issue. When I flush toilet in bathrooms on second floor, I hear the water dripping sounds under the ceiling while standing on ground floor,below bathroom.
Now if I flush toilet in bathroom on ground floor right below bathroom on second floor, i do hear same dripping sounds at the same spot in roof.
May be normal. If you gently add 1/2 cup of water to the toilet bowl, do you hear the same dripping sound? You may be able to reduce the time of dripping by adjusting the bowl refill down a bit.

The roof has a vent pipe, and sound can travel through that.
 

Mdmm55

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I did reduced the water going to fill the filling tank (in that bathroom) and the dripping sound is gone now.
Do i need to solve this problem by replacing any part inside the water filling tank in this bathroom ??
 

Reach4

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I did reduced the water going to fill the filling tank (in that bathroom) and the dripping sound is gone now.
Do i need to solve this problem by replacing any part inside the water filling tank in this bathroom ??
Maybe. I proposed reducing the refill but not the tank level. Some fill valves have adjustable refill, so you can reduce refill without lowering the tank fill. Korky platinum top is one, but there are others. Or replace the refill tube with one that has a pinch clamp. https://www.homedepot.com/p/Fluidma...ip-with-Adjustable-Roller-Clamp-215/202510400

Or just be happy that the dripping is not a leak, but just water dripping over the weir as the toilet finishes filling.
 

Mdmm55

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thank you very much, Reach4 for great help. The tube inside filling tank is small size, compared to your suggested tube. Should
I replace the whole filling apparatus ??
I have attached the pictures for your review, please.
val 1...jpg
val 2...jpg
 
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