Groundwater - Outdoor Faucet Supply

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Johnmcelhany

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Hi all,

I had evident water damage to floor and drywall around an exterior faucet. I’ve opened up the wall and have confirmed that there is no split or leakage from my the frost free valve or supply connections.

Supply is with 1/2” copper from slab. Where the line exits the slab, water pools after cleaning it out several times. I have closely monitored my meter with not as much as a single tick on the drip dial. I’m starting to speculate encroaching groundwater, as it has been extraordinarily wet here.

Thoughts on my troubleshooting and recommendations on sealing the rough-in space around the supply line? Considering hydraulic cement, but not sure if I wasn’t it on the copper line.

Thank you.
 
You might be better served by addressing the source of the excessive ground water.

Gutters might be clogged and overflowing.
Downspouts might be dumping water right at the house or not far enough away.

Yard grading might be poor, not sloped away.

Neighbors might be improperly dumping their rain water or sump pump discharge onto your yard.

Go outside during and right after a strong rain, and evaluate the situation.

Look for standing water or any streams running across the property.
Check for gutter flooding.

If water is coming uphill through the slab, either it is just wicking up slowly by surface tension, up the sides of the hole, or there is standing water somewhere nearby that is higher than your slab.

Carefully chipping out around the copper riser and creating a pocket to receive some hydraulic cement should be safe and successful, if the problem is just capillary action from water creeping up along the pipe from under the slab.

Try to create a pocket around the pipe that is straight sided, or even better, a little wider at the bottom.
Suck up the dust and chips with a vac, so the pocket is clean.
You can moisten it slightly with a damp rag, no standing water left in there.
You can even pack it if water is still very slowly coming in, just sponge it out and pack it quickly and firmly.
But more likely to work without active seepage.
Pack it in firmly with a wood scrap or your fingers, then wash your hands, it dries out your skin.
Hydraulic cement expands while setting.
If the pocket you carve is not shaped properly, the plug will rise up, or will never seal properly.
 
Last edited:
Also, don’t take the meter’s reading as proof there is no leak. A positive way to be sure is to put a water pressure test gauge on the faucet.
1. Open the faucet and watch hand note actual water pressure
2. Tap the gauge to be sure the gauge’s hand is free
3. Note (mark) on the gauge face the hand’s position, be exact!
4. Watch gauge for 15 minutes.
5. If it moves and shows a pressure drop, water is going somewhere.
6. If pressure does not fall after 15 minutes, loosen the swivel connection between gauge and faucet slightly to allow a small amount of water to drip (leak). Let gauge hand fall approximately one pound. Retighten the connection. Again, if pressure doesn’t fall, you have no leak. If it climbs back up, then the meter is leaking past the stop before the meter not allowing a good test.

If indications are you have a leak, check the most obvious culprits first:
* leaky faucets
* hydrants
* water piping above ground
* running commodes
* appliances
* yard sprinklers

As you saw when checking the accuracy of the pressure gauge, a spoon full of water with show up on the gauge Immediately. A true indicator of the smallest leak.
 
HWSleuth, it would seem like you would first have to turn off the city water at the meter before doing this test.
To test the remaining pressure of the water already in the system?
Maybe I am not following?
I don’t see how pressure would ever drop at the gauge attached to the faucet, even with a leak, if the meter was still open.
 
After further testing, including a pressure test, I’ve determined it to be a slow leak in the supply below the slab. The area stays dry with the main off and there slow leak-down under pressure (under 5 lbs per 15 min). I’ve blown the line out and can faintly hear the air escaping.

See photo from build rough-in. I would assume a split or pinhole within or just under the slab given the water intrusion.

Right now, without another option to cap the line, considering delicately drilling holes adjacent to line in order to chisel for access. Not exactly sure where the supply is tied in to the rest of the house, but speculate a half-bath near the main supply cutoff in the center of the house.

Advice is much appreciated. Thanks in advance.
 

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