My supply line comes into our house into the finished room in the basement, Goes into the meter. Then it goes up vertically and then splits, one goes to an outside spigot, and the other goes to a house water filter and then to the house plumbing.
If noticied lately that then is water dripping from the pipe and water filter, I tightened the filter, and wiped down the pipes. It seems to be related to how much laundry (washing) we are doing. At least that is when I noticied it first, was X-mas, when the kids got a lot of clothes. We did about 15 loads of laundry for two days. Could it be from the constant running of water into the washer, and the room being heated???
I use to have insulated pipe wrap on most of that section, but that got all wet so I took some of the wet part down.
It IS related to the amount of humidity in the air and the temperature of the incoming water. If doing the laundry is causing the humidity, then yes it is a function of the heated room, and the cold water.
Heated air can hold more moisture, so that its dew point is below the temperature of the water.
Is the dryer vented to the outside? If so, check the connection from the dryer to the vent to be sure nothing has dislodged causing your dryer to spew moisture-laden air into your house.