Plumbing Pipe Leak: Signs, Causes & When You Need a Plumber

Signs of a plumbing pipe leak

• A water meter that moves when no water is in use.
• Damp, stained or bubbling walls, ceilings or floors.
• Musty smells or visible mold, especially near bathrooms, kitchens or the water heater.
• Warm spots on a floor, which can point to a hot-water line leak.
• The sound of running or hissing water when everything is off.
• Lower water pressure than usual, or an unexplained rise in your water bill.

Common causes

Leaks come from a few recurring sources. Aging or corroded pipes can pinhole or crack. Fittings and joints can loosen or fail, and supply hoses for washers and toilets can burst. Freezing weather can split a pipe, and high water pressure can stress joints over time. Tree roots and shifting soil can damage buried lines, and appliance connections such as a water heater, dishwasher or ice maker can also leak.

A simple meter test for a hidden leak

The U.S. EPA WaterSense program suggests checking your water meter before and after a period of about two hours when no water is being used. If the reading changed, you probably have a leak. Its guidance also estimates that the average household loses close to 10,000 gallons a year to leaks. EPA WaterSense: Fix a Leak Week

To narrow it down, close the main shutoff and check the meter again. If it stops moving, the leak is on the house side. If it keeps moving, the leak may be in the underground line between the meter and the house. Toilets are a frequent silent culprit; adding a few drops of food coloring to the tank and waiting about ten minutes without flushing shows whether color leaks into the bowl.

What to do first

1. Close the stop valve at the leaking fixture, or the main shutoff if you cannot find the source.
2. Keep water away from outlets and appliances, and turn off power at the panel only if you can do so while dry.
3. Dry and ventilate the area, and photograph the damage for your insurance claim.
4. Use towels and a bucket to limit spread. A repair clamp or wrap is a temporary measure only.
5. Call a plumber to find the source and repair or replace the section.

When to call a plumber

• Water is spraying, flooding or cannot be stopped by closing a valve.
• The leak is inside a wall, ceiling or under a slab, or you cannot find it.
• The meter still moves after the main shutoff is closed.
• The same pipe or joint keeps leaking after a repair.
• You see spreading stains, sagging drywall or mold.

For active leaks that will not stop, see emergency plumbing. For non-urgent leaks, see leak detection and repair. A leak at the water heater is covered on the water heater repair page, and recurring backups are covered in drain cleaning.

Questions to ask before approving work

Pipe leak questions homeowners ask