Pipes "thud" when water is turned on or off anywhere in the house

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Flyover

Trying not to screw things up worse
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The house was built in the late 70s. Single story ranch with a crawl space. The pipes are copper. The previous owners were cheap. The thud is loud.

So, what causes this kind of thing? Does it have to do with the placement of the pipes? How they're mounted under the floor? In the plumbing system itself? Is it just a normal part of having copper pipes and hardwood floors?
 
Sounds like water hammer to me. Here's a video from This Old House that may explain what you're going through. [ame]https://www.youtube.com/watch?v=_Cu9LUx79w4[/ame]

PS> I'm not advocating the use of a water arrestor, just pointing to the video to see if it describes the problem and why it' happening.
 
you can stop water hammer by shutting off the water to your house and opening all your faucetsinside and outside till all the water is drained. Then shut the faucets and turn on the water where you shut it off. There are good explanations of what water hammer is by googling it.If the noise is from pipes banging against something , get some "great stuff foam" and spray the area
 
crawl under the house and have someone turn the water on and off
locate the area of the bump.
a lot of times it where the water pipes come up threw the floor. cut a wood shim and drive it in the annular space
between the hole and pipe.

or cut a 2x4 to nail next to a pipe , use a copper 2 hole strap to secure pipe to 2x4
 
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Thanks everyone, these are helpful ideas. I'll check it out and get back to you.

[UPDATE] So far the videos I've found on "water hammer" don't sound like what I've got going on. The water hammer in the videos sounds like tapping or rattling.

Maybe it's the sound quality of the recordings, but when water is turned on or off my pipes really sound like a large 30 pound sack falling onto a hardwood floor in the next room over, with a kind of deep rumbling sound mixed in that lingers for a few moments after the initial thud.

I do think it probably is water hammer though, given the mechanism of how it works.
 
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If possible:

- Locate where the noise is coming from
- See if you can access the plumbing at that point
- Post up a video of the problem.

Maybe a fresh set of eyes can help you pinpoint this thing a little better.
 
The exact sound of water hammer in your house could vary depending on how the pipes are fastened to the joists, studs, etc.

The reason why draining the pipes sometimes stops water hammer is that air bubbles may remain behind in the pipes and act as shock absorbers.

Installing a water hammer arrestor is a more reliable and longer lasting solution, although some varieties of water hammer arrestors require draining the section of pipe in question every few months.

The best place to install a water hammer arrestor is near the faucet that causes it.

Note: A loose washer or trapped sediment in a faucet can also cause water hammer.
 
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