About 2 weeks ago, when I turn on the cold water tap in my upstairs and downstairs bathroom the water comes out super hot for about a minute or so and then starts getting cold. I have had no plumbing work done, no hoses crossed, etc. Here's a few other things I've noticed. I hear a noise; it's a rhythmic plop, plop noise. I followed it down to the basement and it seems to be coming from some piping near the water heater. No visible leaks anywhere. Then I heard it in the upstairs bathroom; it seems to come from the wall that the bathtub fixtures are on; I turned on the bathtub spout thinking maybe there was some water in the line and I didn't seem to hear it but maybe that's because the water noise covered up the noise. We have ceramic floor tile in that bathroom and I felt a warm spot on the tile as I walked across it. Our sink and toilet are on the same wall and the tub is across from them. I have a tub control which I don't like; It's a one lever fauctet control. Off is in the 6:00 position. It moves counter clockwise up to the 12:00 position. The 6:00 position is cold and as I turn it counter clockwise it gets hot. My water heater is only 4 years old, but I don't seem to get hot enough water and it never lasts long enough. The highest temp I can put it on is 150 degrees; It also has a "smart" setting, an "energy smart:" setting and 2 settings for low/vactation use. Now that this hot water coming out of cold taps problem has started, I really don't get the water as hot and doesn't last as long as it used to even though like I said it never really was hot enough. It seems that after I turn on the cold water tap, and run it, the hot water is super heated or something and then it's not hot enough when I use it for a shower. The kitchen sink doesn't have this problem which is on the floor level between the downstairs bathroom and the upstairs bathroom. Any help greatly appreciated. Thanks

Is the ceramic tile on a concrete floor? Look outside at you water meter with nothing on and see if the meter is moving. Then turn the valve off at the water heater and after 10 seconds turn it on slightly. Do you hear water running? If so, it is likely you have a hot water leak under the concrete next to a cold pipe. The very hot hot water is simply leaking on the cold side pipe as it sits. If you are so lucky as to have a 'slab leak', you can expect to spend between 400.00 and a thousand dollars to open the floor, repair the pipe, and close the concrete floor. Floor covering extra.

Actually, I am answering my own question as I have figured out what the problem was. My son started taking showers in the downstairs bathroom and wasn't turning the hot water valve off all the way; consequently the water was also dripping from the handle. I turned it off and some time later cold water was coming out of the taps again. Thank you all for all the help you gave me.