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water leak

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Joined: Nov 4 2004

Yes, another post on this popular topic (alas). My situation is a bit unusual, as you will see.

The symptom: A slow leak that leaves water on the floor. (That is, after I moved the water soaked carpet and pad away...) The water is located near, but not directly under the kitchen sink. I have already disconnected the dishwasher, so that is not the problem. After shutting off the water main and mopping a few times, the water eventually dried up. After a couple of days, I turned the water back on for an hour to try to estimate the rate of flow, and within 40 minutes there was a patch of water about one foot square. However, I did not observe any change in the water meter dials. (Mine does not seem to have a continuous flow indicator as some apparently do.) From what I can see, the leak is perhaps one pint or one quart per hour.

My first thought was that the leak was in the wall, in the pipes going to the sink. However, a plumber said it could just as easily be in the slab. This assumes, does it not, that the pipe runs within the slab rather than under the slab? I can't imagine how the water would rise up to floor level if the pipe is penetrating directly through the slab to the ground.

Everything I have seen on this web site says that Eicher domestic water pipes run under the slab. But my house is a very unusual Eichler: My house has original forced air radiant heat. A forced air furnace pushes hot air through the slab, where it heats the slab and exits via floor registers located in every room. From what I can see peeking down the registers, there are large voids (from 3" to 5" below the surface) and one deep channel (from 4" to 12" below the surface). (The description I included in a post to the grabbag was apparently based on faulty recollection.) There is no boiler based radiant heat.

So, who knows where the pipes are.

The leak is in an area that is adjacent to the deep channel. It may be in an area with no voids. I suspect there are no voids under load bearing walls.

The plumber recommended that patriotic leak detection service, but when I called them they said that their technique for finding leaks is not reliable when the flow is less than 3 gallons per hour, which seems to be the situation here.

I would appreciate any advice or recommendations. (You can send recommendations to me by email. Use the name courtyard and the domain cbfiddle followed by the usual dotcom.) If they cannot find the leak, are there other ways? I suppose it might be worth $250 just to find out where the pipes actually are.

Another question I have: I've seen reference to a "manifold", and I'm guessing I have one (or two). It is in a closet near the large bathroom, small bedrooms, and laundry area. I figured these were distribution points for hot and cold water, but it is just for things nearby or is it for branches to the whole house? One group has 4 pipes, the other has 5. I figure there is one destination that needs only cold water. It would make sense if the destinations are local: laundry, tub, sink, and toilet.


Joined: Mar 20 2003

I would guess that the pipes are laying just below the slab but they would have to penetrate the concrete slab to supply water to your faucets in the home. You could have a leak right near the top and perhaps you can open up the wall to check. If you can access it from the back, perhaps you could pop off the paneling to check for a leak.

I have protected my domestic pipes from further corrosion and future leaks by cathodically protecting the pipes. Here is discussion about that topic:

The radiant heat companies that advertise on this site can also detect leaks in domestic water pipes. Anderson is excellent and I hear Franz Rogmans is also good.

Let us know what happens- its always helpful to others. Good luck.

Joined: Nov 4 2004

What I wound up doing was removing the baseboard trim and cutting out a small piece of the panel that was hidden behind the trim. That allowed me to observe that the water was coming up out of the slab, and further experimentation determined that it was a hot water leak. Now I just need to decide between a minimal repair, a minor retrofit, a complete retrofit, or using this as a good excuse to do a major remodel. (There are fortunate circumstances that allow the current broken situation to be tolerable for a while.)

Joined: Mar 20 2003

If you aren't already, turn off the water main when you aren't using the water to prevent tons of water from dumping into your slab and ground beneath until you get it fixed. After 4 months of living in our Eichler with a new baby (6 years ago), the city of Palo Alto knocked on our door to see why we were using so much water. Thanks to Glen Wagner at Anderson, we had it fixed fairly quickly.

Joined: Aug 30 2003

You live in a a Palo Alto Eichler with original forced air heat? Can I ask where in Palo Alto, and what year your house was built? I am very surprised. There are Eichlers in Southern California with forced air heat, but I have never heard of any in the Bay Area.


1959 A. Quincy Jones atrium model in The Highlands, San Mateo

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