Why does the cold line sweat?

Condensation forms on cold surfaces when warm, moisture-rich air comes into contact with them. Because the cold water running through your cold water line pipe keeps it cool, the air near it is cooled as well. If this cooled air is unable to hold all of the moisture it contains, the water vapor must condense and form liquid droplets on the cold surface of the pipe, causing it to sweat.

The following factors affect the occurrence and severity of sweating:

- Temperature: The colder the surface, the more moisture it can hold. Thus, the colder your cold water pipe is, the more likely it is to sweat.

- Humidity: The more moisture-rich the air, the more likely it is to condense on a cold surface. When the humidity in your bathroom or kitchen is high, the cold line is more likely to sweat.

- Air movement: Air movement helps to carry away moisture vapor. When the air around the cold water line is still, it has a greater chance of condensing than when it is moving. This is why you're more likely to see sweating on cold water pipes in places with poor ventilation.

To reduce sweating on your cold water line, do the following:

* Keep the temperature of your cold water supply line as warm as possible. This will help to prevent condensation.

* Vent the areas where you have cold water pipes. This will help to circulate the air and prevent it from becoming overly humid.

* Insulate your cold water lines. This will help to keep the water colder and reduce the amount of condensation that forms on the pipes.

* Use a dehumidifier to reduce the humidity in the air.