# Help me diagnose a hidden water leak? **URL:** \ **Category:** Factual Questions\ **Created:** [October 27, 2011, 5:35pm UTC](https://boards.straightdope.com/t/help-me-diagnose-a-hidden-water-leak/600988 "2011-10-27T17:35:11Z")\ **Posts on this page:** 8\ **Page:** 3
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [October 30, 2011, 3:19am UTC](https://boards.straightdope.com/t/help-me-diagnose-a-hidden-water-leak/600988/41 "2011-10-30T03:19:58Z")
> [@papergirl](#): > > All good advice…I’ve learned so much! The good news, I think, is that I found out that the pipes are only under the slab as far as the water heater (that main valve, I mean). Then they branch off into the walls. That’s good because I always assumed they were all under the slab. > ETA: Except the kitchen sink. Looks like that must go back under the slab, probably. > Anyway, I have a much better understanding of where my water lines are! You should be able to see if the main shutoff in the house goes back into the slab. If it doesn’t then the remainder of your plumbing is in the walls. And if it isn’t then you can always route stuff through the attic to bypass anything in the slab past the main shutoff valve. Do you have outside faucets that come up through the slab and into a wall? ---
**Author:** ![papergirl](https://avatars.discourse-cdn.com/v4/letter/p/aca169/32.png) [@papergirl](https://boards.straightdope.com/u/papergirl)\ **Post date:** [October 30, 2011, 7:02pm UTC](https://boards.straightdope.com/t/help-me-diagnose-a-hidden-water-leak/600988/42 "2011-10-30T19:02:47Z")
The spigot in the garage looks like it comes off the slab waterline. The outside one, as far as I can tell from the pipe configuration at the shutoff valve just above the slab, goes through the wall along with the washer and bathroom lines. If I find a leak under the slab, I think I’d do just what you suggested. That would be the least invasive way to go, anyway. But I’m pretty sure I don’t have a leak under the slab…my repair guy is coming in a few days to install a new faucet so I’ll double check with him. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [October 31, 2011, 12:52am UTC](https://boards.straightdope.com/t/help-me-diagnose-a-hidden-water-leak/600988/43 "2011-10-31T00:52:14Z")
If you have to run pipes in the attic box them in and vent through the ceiling so the house heat keeps them warm. ---
**Author:** ![amarone](https://avatars.discourse-cdn.com/v4/letter/a/e0b2c6/32.png) [@amarone](https://boards.straightdope.com/u/amarone)\ **Post date:** [October 31, 2011, 2:18am UTC](https://boards.straightdope.com/t/help-me-diagnose-a-hidden-water-leak/600988/44 "2011-10-31T02:18:11Z")
I had a leak that was consuming about 2,000 gallons a month. The plumber checked the water pressure and identified a faulty pressure valve where the water enters the house. It was supposed to hold the water back when no water was being consumed, but was not working. I have no idea where the water then went, but replacing that valve fixed the problem. ---
**Author:** ![papergirl](https://avatars.discourse-cdn.com/v4/letter/p/aca169/32.png) [@papergirl](https://boards.straightdope.com/u/papergirl)\ **Post date:** [November 3, 2011, 1:03am UTC](https://boards.straightdope.com/t/help-me-diagnose-a-hidden-water-leak/600988/45 "2011-11-03T01:03:00Z")
I went in to pay the $114 bill today. Having tentatively decided this was a billing-cycle issue rather than a water leak, I asked the woman to check the read date on that bill. Sure enough it was for Aug 8-Sept 8, the height of the most recent dry spell when I was water my gardens. She looked at my most recent reading and it was only 3600 gal, which is less than the usual 4000 even. So…I don’t have a water leak, AND now I know several ways to troubleshoot for one! Thanks so much to everyone who took time to advise me. ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [November 3, 2011, 10:01am UTC](https://boards.straightdope.com/t/help-me-diagnose-a-hidden-water-leak/600988/46 "2011-11-03T10:01:25Z")
Well, that’s a relief! ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [November 3, 2011, 2:04pm UTC](https://boards.straightdope.com/t/help-me-diagnose-a-hidden-water-leak/600988/47 "2011-11-03T14:04:01Z")
having paid the bill then ‘that’s water over the dam’. ---
**Author:** ![chiroptera](https://avatars.discourse-cdn.com/v4/letter/c/df705f/32.png) [@chiroptera](https://boards.straightdope.com/u/chiroptera)\ **Post date:** [September 2, 2014, 10:24am UTC](https://boards.straightdope.com/t/help-me-diagnose-a-hidden-water-leak/600988/49 "2014-09-02T10:24:39Z")
> [@sukacagi](#): > > may be this video help to you > > [http://www.youtube.com/watch?v=6K9MJaTIb\_U](http://www.youtube.com/watch?v=6K9MJaTIb_U) Reported. [Previous page](https://boards.straightdope.com/t/help-me-diagnose-a-hidden-water-leak/600988.md?page=2)