Contractor Talk - Professional Construction and Remodeling Forum banner
Cancel
Create thread New Forums

pipes knocking when water is running

Jump to Latest
1 - 20 of 22 Posts
N

nickko

· Registered
Joined
·
2,961 Posts
Discussion starter · #1 ·
Hi.
just recently my water pipes in my house started making a knocking noise when the water is running. It is not water hammer like when you shut the water off. It is a constant knocking noise when the toilets are filling or when the washing machine is filling. It seems to be when there is a high volume of water. Not a bathroom sink or kitchen sink but if i turn on my laundry sink full blast i also get the knocking.
I have a back flow preventer and a pressure regulator on my water line. Could one of these be the culprit ? I have been living here for 25 years and this just seemed to start a few months ago.
When i was having a footer dug for my room addition I forgot about a water line that i had running up to my shed and the guy hit it and pulled my copper line under my house. Nothing broke but it put a very slight curve in the copper 3/4 line. It is barley noticeable. I am not sure if that is when it started but i wouldn't think a slight curve in the line would cause a constant knocking noise when the water is running.

Thanks......nicko
 
Discussion starter · #8 ·
Ok
i guess i should have just ask what are some things to look for.
I will have to run the water and check it out. I should have done that in the first place but i never think of it until i hear it.

Thanks
 
#9 ·
Shut main off. Open outside bibs full blast & let run a few minutes. Turn main back on. Check. Could be regulator, a bad valve or any # of things. Loose shower head line maybe. Did you say you did an addition. Add any plumbing. My guess again guess, is a bad valve


Mike
 
#10 ·
Just remembered an issue i have come across, fill valve on Toto toilets from about 6 years ago. 3 or 4 jobs I have seen this on, pipes shudder when water is used, not when toilet is flushed. Took a long time to figure it out, maybe its the same problem. Plumber turned off toilets 1 at a time for a day or so and found out which one it was. He heard about it from another plumber.

Maybe you have a similar issue
 
Discussion starter · #12 ·
I’ll have to do some investigating. I did not add a bathroom. All valves in my house are ball valves. I will check the toilets. Sounds like it could take some time to figure out. Maybe I’ll get lucky and find it without to much trouble.
 
#13 ·
An HO I did some work for had a similar problem, pipe would rattle when upstairs sink hot water warmed up.

We never did anything about it, but I was considering drilling holes in the (interior) wall bay and shooting window foam in there.


Sent from my iPhone using Tapatalk
 
#14 · (Edited)
Check your water heater. Sediment buildup in your water heater is the most common reason for inexplicable banging noises when there's no water running. It may be loud enough that the echoes carry and cause it to seem like the knocking noise is coming from the pipes in the wall. The noise is the steam bubbles escaping from the accumulated sediment at the bottom of the water heater tank. It's similar to how, when you boil water in a covered pot on the stove, it begins pushing up against the lid. Flushing your water heater can help rid of these noises if water isn't running.

Beyond that:

As we all know, the knocking noise is caused by the expansion and contraction of water within the metal or plastic pipes in your house. When water runs through a pipe it heats up or cools down, causing it to expand or contract.

You ruled out a water hammer which is typically when you hear a noise only when you stop a flow of water and not when the water runs. First thing to do is check the check valve springs in the faucets or any other check valves.

High water pressure is one of most common causes of water pipes knocking. Water pressure that is too strong could shake the pipe despite being secured in place on the walls.

Loose supply pipes in your bathroom. Problems happen only if the water runs, and if the banging noise stops when shutting down water, it's a good indication there's a leakage.

In many cases knocking pipes are simply due to loose elbows or valves that aren't completely open or closed.

If the banging sound is coming from a water supply pipe, make sure that all valves and faucets are fully open. If this doesn't solve the problem, try turning up the water pressure in your house by adjusting the main valve to your property. This will often get rid of excess bubbling or gurgling noises between air chambers that result from low water flow rates.
 
Save
Reply Quote Like Like
#16 ·
rrk said:
I have never seen anything inside a water hammer arrestor, here they are usually capped vertical sections of pipe between 1ft and 3 ft long filled with air. Even the smaller ones are shorter but larger diameter.
Click to expand...
I meant to say to check valve springs in the faucets or any other check valves. I correct it.
 
  • Like
Reactions: rrk
Save
Reply Quote Like Like
Discussion starter · #18 ·
thanks for the help. It is going to be my weekend job to investigate. Like i need more things to do. I only have a room addition I'm trying to finish and a couple other projects that kept up along with two grandsons that live two houses away.
 
1 - 20 of 22 Posts
About this Discussion
21 Replies
9 Participants
Last post:
nickko
Contractor Talk - Professional Construction and Remodeling Forum
posts
3.6M
members
169K
Since
2003
A forum community dedicated to professional construction and remodeling contractors. Come join the discussion about the industry, trades, safety, projects, finishing, tools, machinery, styles, scales, reviews, accessories, classifieds, and more!
Full Forum Listing
Explore Our Forums
General Discussion Tools & Equipment Business Painting & Finish Work Decks & Fencing