Mysterious Water Main Leak

D107

Got a water alarm this morning from water dripping from our inside basement wall --a foot from any main connections. We had our individual lawn sprinklers going full blast a few times in the last few days and again this morning. 3/4" copper, looks like K-44 from the photo. Is that standard? Drip stopped when water was turned off, and only shows if there's significant flow. Ground right outside was damp--only in one place--that area wasn't being watered at the time. Checked all inside plumbing lines and main connections-none wet.
New main was installed three years ago; unfortunately warranty is only one year. SMaybe it's a pinhole leak?--It may only leak with prolonged high water usage which it hardly sees with us. May have been there from the beginning but doesn't show until ground is saturated. Perhaps they could just open ground up and replace part that's leaking?

Larry Weingarten

Hi, The only way to really know what's going on, is to cut out the section of pipe and have a look inside for erosion. Another approach is just to silver solder the leak shut and see what happens. What does your water quality report tell you about your water? Not sure about the k-44 designation. I'm used to type M or L. Does your pipe have a blue stripe down it's length?

Yours, Larry

D107

Thanks Larry. Will look for water report. No blue stripe from the photos I took. K copper is supposed to be thickest. Usually has green stripe but my photos may not have been comprehensive enough to show that.  Question is can anyone tell from writing on the pipe in the photo if it’s American made? The old galvanized lasted 100 years and this for just 3?

mattmia2

I cant see any reason why flow would cause it to leak. Flow could make it cold and cause condensation, but that wouldn't make the ground wet unless the pipe is basically at the surface and the water is very cold and the dewpoint is very high.

Where is the sewer line? That would only leak with use.

D107

Agreed it is very strange. Sewer line is 15 feet away no possibilities there. Our inside water pressure is set around 50psi; street pressure is higher. If the street connection 25 ft away was compromised could water travel up from that into house?

There’s been no dripping since sprinklers have been off. When I turned slop sink faucet on hard, dripping started again.

mattmia2

Where are the sprinklers connected? Where is the backflow preventer for the sprinklers? The water line could be damages or spliced near where it enters the house but leaking only with flow doesn't make sense. Sweating with flow makes a lot of sense but does not explain why it is wet outside.

D107

We have only individual lawn sprinklers not a system. Installer will be coming tomorrow so hopefully we’ll know more. We have two outside hoses, front and back. Back hose was on during leak, nowhere near water main. I guess incoming water can get quite cold during long run periods but how does the condensation push through a wall?

D107

Water was coming in about a foot to the left of the main (if you were looking directly at the brick wall and the main was on the right) as you see it in the photo. So theoretically if there was a leak on the main the water could pool and come through nearby. The entry point for the main was sealed in and out with special cement plus caulk in the sleeve. (The ground above is no longer wet; perhaps it was originally dew I can't say. I think it would take a lot for water to well upwards through four feet of ground instead of just following gravity.)

mattmia2

Perhaps the water outside was from a leak in the gutter or something like that and the water inside was condensation.

Jamie Hall

Um... step 1? Have you pressure tested the lines which are potential culprits? Do they hold pressure?

D107

The plumber came out today and we found that behind the styrofoam that was installed on the inside wall were two large holes. One was a rotted wooden box (wood was moist and we removed it) likely used to connect the oil tank feed from years ago. the other looks like a brick had fallen out and was partially repaired. Around the small hole is about where the water was coming from behind the styrofoam. The wooden box was deep--almost the width of the wall--so after we keep an eye on this for a few weeks with normal usage, plumber suggests filling holes with hydraulic cement. For added insurance and $$ we could excavate and seal also from outside. But over 24 years despite this condition, only once or twice in the heaviest of rains have we ever had slight leakage.
@Jamie it's a small house and we pretty much know where all the piping is and none of it seems within range to be connected to this issue either leak or condensation-wise, but we'll stay open to that possibility. The plumber suggested we keep everything open for a few weeks, use the water normally and see if the problem re-appears, then seal the holes up. We've had the hose on now in the back for more than an hour with no seepage. @mattmia2 I'll double check any gutter blockages.

ChrisJ

Type K soft copper is what's normally used for a buried water service.

Type K is thicker than L and M is the thinnest.