Water problem that defies diagnosis

[Fleur@capemay]

Two year old new construction, two story home with a small third floor room with a deck. Bedrooms are on the first floor, kitchen and living area on the second floor. All three levels have decks with separate outside water lines. City water with PVC pipe and tankless manifold hot water system. Entire home flooring is tile, set in mud. There is a crawl space under the house where the city water meter connection is. Second home, so we shut the water off when we are not there.
Problem started last October, went to the house turned on the water and left to get groceries. Returned about an hour later and the second floor kitchen area had a significant amount of water running the length of kitchen from the refrigerator to stove parallel with the sink.
While we could never make the water spring up through the tile it repeated several times. We could identify the exact spot and watch the water "spring up" Occurred when the water was turned on and occurred when the water was turned off at 5:00 am, happened when the water was on, in the middle of the day. Replaced the ice maker and repaired the kitchen sink water hook-up. Builder tore the ceiling out under the leak to watch for wet pipes. Purchased a moisture detector from Home Depot and can not detect moisture anyplace. Nothing happened and we were away from the house November to April.
Returned in April, power washed all three decks using water at each level. Returned a week later. Turned the water on and a significant pool of water was in the center of the second floor living room and now the third floor living room.
The ceilings, walls, and baseboard are dry and everyone is baffled with why the water is spring-up not flowing down and the ceilings are immaculate.
Builder, architect, and plumber think it is rain water, there appeared to be a correlation between heavy rain and wind but the leak also occurred during dry weather. Had the leak water tested and it has a high ph and identical profile to our tap water. Tested the rain water which had a very low or no ph. Leak has not repeated for two weeks. Would greatly appreciate any direction. An infrared camera has been suggested, would this help?
Thank you

 

[NHmaster3015]

How about a leak in the drain pipe

 

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[DougB]

You say the entire home has mud floors and tile. It sounds like the water is traveling between the mud and the tile.

Maybe, when under pressure the leak stops. Then when you relieve the pressure, the leak opens up. You apply pressure, it leaks until the pressure builds, and then seals.

Have you tried turning off the water, draining the plumbing at the 1st floor hose bib, and then turing the water back on - open the highest faucet - let it run - so there's little water pressure - but water flow - for a minute or two. Then turn it off. See if this makes a leak.

Maybe it's caused be a flucation of the city water pressure?

 

[DougB]

Another thought: You say there was water in the third floor living room - in the middle.

This would lead one to believe the leak is in third floor - since water doesn't flow up.

Second the water is in the middle of the floor because that's where the deflection (sag) is greatest.

One thing to try is to pressurize the water system - I don't know the max allowable - maybe 100 psi?? See if it holds.

Same could be said for a vaccum test.

 

[Fleur@capemay]

I will try your suggestions this weekend. I also wondered about fluctuation in the city water pressure. How could that be tested? Neighbors are not experiencing the same problem. Think you are right about the pressure appears the majority of time when the water is turned on after being off for at least a week. It did occurred once in the middle of the day and one time I shut the water off at bedtime and woke up to water on the floor in the morning before turning the water back on.
Thank you and will let you know how the test goes over the weekend.

 

[Fleur@capemay]

Can a lay person pressurize the water system or do a vacuum test? Ask the plumber to do them?
Thanks Again, very much.

 

[DougB]

I will try your suggestions this weekend. I also wondered about fluctuation in the city water pressure. How could that be tested?

You would have to contact a testing company that has pressure sensing recording equipment. It would be attached to your water line and record the water pressure at some interval (like every minute?).

For a pressure test a plumber would use compressed air.

I wonder if there is a vaccum break, or backflow preventer (on the 3rd floor - since that's the highest point that leaks) that is malfunctioning / discharging. Ask the plumber if there are any of these valves in the 3rd floor bathroom.

 

[Fleur@capemay]

There are backflow preventers on the outside faucets. You have given us solid leads. Really appreciate your time and advice.