After using 100m^3 extra water last year, I installed a Raspberry Pi with a camera to look at my water meter. Soon it will be able to cut off the water on excessive drain (like a forgotten garden hose). I have stopped the toilets leaking, and now I'm down to losing about ½liter per hour. It is on the hot water (shower) circuit, If I close the hot water, no drain.enter image description here Each little blip on the graph is 1/8 turn of the 1l dial on the meter, i.e. 0.125l. Hot water turned off at 11:20 Here the hot water is turned off at 11:20

It must be under the floor. In the bathroom (but the plumbing is in the wall) and the boilerroom, the floor is tiles on top of concrete, then some isolation. In the kithen I believe is (from bottom) earth, concrete, insulation, chipboard, floorboards, but the pipes just comes in from the boilerroom, then up to the sink.

It can't be upstairs; a bucket of water would be noticed. If I just monitor the loss, and it does not get worse, is it worth going through the concrete to find this small leak?

[*] For non-metric, each blip is 1/4 pint, 1/2 cup, and the loss is about 2½ gallon per day. enter image description here

The software is an adaption of https://blog.m.nu/vattenmatning-med-raspberry-pi-och-webkamera/ in Swedish, I'm afraid.

I could put it on github I guess...

There is a gap between the pressure valve outlet and the drain, but I have left a cup there for 15 minutes, and it is completely dry.

  • Are you sure your pipes are actually buried in the concrete? Seems strange that they're on the outside of the thermal envelope of the house (below insulation), but then I'm not that familiar with on-slab construction (and this sounds like an older non-North American construction, since you mentioned both chipboard and floorboards). – gregmac Mar 24 '17 at 16:16
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    I'd also try to further isolate the leak before tearing up concrete. Turn off shut-off valves to fixtures, and install them if you don't have them. It's possible there's a leak in a wall or something too. You should also check the T&P valve on your hot water tank, those do leak sometimes and usually setup so if they open the water goes down a drain, that might go unnoticed. There should be an air gap, so you could put a bucket or something underneath to see if anything is coming out. – gregmac Mar 24 '17 at 16:20
  • I agree with @gregmac in that the leak isn't necessarily under the floor. Spend a bit more time isolating where it is – mmathis Mar 24 '17 at 16:21
  • At least in the bathroom and boilerroom it is tiles on top of concrete. Only in the kitchen is with wooden floors, and the outlet is just 10 cm in from the boiler room. Fixtures are not leaking. – Lenne Mar 24 '17 at 16:29
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    I agree with @gregmac it may not be a leak at all but the pressure fluctuations from the hot water system pushing some water back through the meter then with cooling water flows in with no real ussage. I have seen this in the past on systems with no check valve you get charged for water going both ways on the meters in my area and no real water was used. A check valve and expansion tank can eliminate this problem. – Ed Beal Mar 24 '17 at 18:57

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