Sweating Pipes and Dripping Condensation

Condensation or Leak? How to Tell

A sweating pipe is wet on the outside, all along its length. A leaking pipe is wet at one spot, usually a joint, a valve or a fitting, and it drips from that one place.

Try this. Dry the pipe with a towel and watch it for about ten minutes. If water comes back along the whole length, it is condensation. If it comes back from one point, you probably have a leak.

A few more clues help:

• Only cold lines sweat. Hot pipes rarely do. If a hot pipe is dripping, suspect a leak.
• It gets worse in humid weather. Summer afternoons in North Georgia, or the days after a rain, make sweating worse. A leak does not care about the weather.
• Taste and color. Condensation is clean water. Leaks can pick up rust, minerals or dirt from the pipe.
• Test with the water off. Close the main water valve. If the dripping stops, it was coming from the pipes. If it keeps going, the moisture is coming from the air, a drain line or somewhere else. The guide to finding a hidden water leak walks through a meter test.

Why Pipes Sweat in Mountain Homes

Water pipes in the ground and in unheated spaces run cold, often colder than the air. Warm, damp air touches them and gives up its moisture. That is the same thing that happens on a cold drink in the summer.

North Georgia homes build up humidity in a few ways. Many sit on crawlspaces with bare dirt, which lets ground moisture rise. Basements built into a hillside stay cool and damp. Homes on a well often have the pressure tank, filters and long cold lines in one utility room, where cold water sits and sweats in warm weather.

Showers, a clothes dryer vented inside, and an unvented bathroom all add moisture too. If the air is wet, the pipes will show it first.

Where You Will See It

• Crawlspaces. Cold supply lines hang under the floor. Drips fall onto subfloor, insulation and dirt. This is the most common place, and the one people notice last.
• Basements and utility rooms. Look at pipes near the water heater, the well tank and any filter housing. Drips on the floor can be mistaken for a leak at the tank.
• Under cabinets. Under the sink the cold line is often the wettest pipe.
• Above ceilings. Pipes in attics or between floors can drip onto drywall and leave a stain that looks like a roof leak. See water stain on the ceiling if you have a mark below a bathroom.
• Toilet tanks. The outside of a cold tank can sweat and wet the floor. If the base of the toilet is wet, see toilet leaking at the base.

What Helps and What Does Not

The goal is to keep warm air away from cold metal. The usual fixes are simple:

• Foam pipe insulation on cold lines. Slip-on foam tubes with the seam taped shut stop most sweating. The seam must be sealed, or air gets in and the pipe sweats under the foam.
• Lower the humidity. A dehumidifier in a damp basement helps a great deal. Vent the dryer and the bath fans outdoors.
• Deal with ground moisture. A ground cover in a dirt crawlspace cuts what rises from the soil.
• Replace soaked insulation. Wet foam holds moisture against the pipe.

Insulation also helps against freezing. If your pipes are exposed and winter is coming, the winterizing guide covers it. Ryan does leak repair and frozen pipe repair, but he is not an insulation or crawlspace company. If the cause is the whole crawlspace, he will tell you so, and you will want the right kind of specialist for that part.

When Sweating Becomes a Problem

Light sweating that dries between humid days is mostly a nuisance. These signs mean damage may be starting:

• Wood that is dark, soft or covered in mold near the pipe.
• Insulation in the floor or ceiling that is wet and heavy.
• Rust or green stains on the pipe or fittings.
• A drip that never stops, even in dry weather.

That last one is a leak, and a slow leak can run for months inside a floor before you see it. The sooner it is found, the smaller the repair. Leak repair with Ryan starts with a free estimate.