How to Detect and Fix Water Running Noise Behind the Wall (Hot Water is only warm)

If you are hearing a water running noise behind the wall and all the taps in your house is turn off, then there is a good chance that the water pipe is leaking. Also if the hot water system is running not very hot then this is a good indication that the hot water pipeline is leaking.

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I heard water running behind my bathroom wall for hours. Turns out I forget to shut my hose off outside. As soon as I shut it off, the noise stopped.