I noticed a water stain under my carpet in my bedroom, what could cause this?

What is a slab leak?

Hi Kieth...

A SLAB LEAK is when a pipe is leaking under the concrete slab of a home without a basement... it can be a heat pipe or a water pipe (hot or cold) or sometimes even a sewer leak (rare). These can be troublesome because water can find a pathway and show up at a spot that indicates the leak is here, for example, but it is actually 10 feet away at another spot underground.

For slab leaks some people use a stethoscope to locate the leak (if pressurized.. sometimes can hear the leak), but most people call in a leak detection company. These people can locate a leak to within inches. Then you or a plumber chops up the floor, digs down and makes the repair.

Now, you said you found a water stain under the bedroom carpet.. Is this bedroom on a slab floor? Is the stain located near an exterior wall or near a bathroom wall? How about heat... any heat pipe near this spot?

Let me know more... O.K.

MARK

Mark nailed it,
Answer his questions. He asked about the location because the water night just be from another source. Let's check, To check to see if you have a hidden leak first shut down everything in the house, no flush, no drinks of water, and if you are on a meter go out and check the little pointer in the gage. It should not move or creep. If it does you have a leak. If you're on a pump then check the pressure gage after the pump builds up to pressure and shuts off. The gage should not fall and the pump come back on. If so then you have a leak. Ok! So now you know you have a pressure leak What's next?
Now you have to pin point it;.You can't go by the hot spots because water, like electricity, will seek the path of least resistance. This means that the leak can be in one spot and the hot spot some distance away.
I live in a area where all out buildings are on slabs so I've had this many times. Our usual way is to call in a leak detection service such as Sleuth. They will detect the exact position of the leak. Take up the slab, bag the dirt and bare the leak. All we have to do is drain the system, replacethe bad piece of pipe and patch the slab.
Another method would be if the plumber knew the exact pipe that was leaking the fixture it serviced and the location of the manifold that supplied it he could cut the line at the manifold, cap it off and look a new line up in the attic and drop down through the wall to pick up the fixture.
Good luck, Tom

Sure, it could be a slab leak as correctly pointed out by our Experts in their responses. But also, it could be: overwatering flowers, slow drip from ceiling (leaky condensation line), accidentally spilled water, dog urine, leak in the wall (water traveling under carpet) etc. I would monitor it for few days first...