Signs of a Slab Leak

Slab leaks often develop beneath a concrete foundation where plumbing lines are hidden from view. While the leak itself may not be visible, it usually creates clear warning signs inside the home. Recognizing these signs early can help prevent structural damage and costly repairs.

Common Warning Signs of a Slab Leak

Homeowners may notice one or more of the following symptoms when a leak is occurring beneath the slab.

• Unexplained increase in water bills
• Sound of running water when fixtures are off
• Damp or wet flooring with no visible source
• Sudden drop in water pressure

Warm or Hot Floors

Warm or hot spots on the floor are one of the most common indicators of a hot water slab leak. Heat from the leaking line transfers through the concrete and flooring.

• Warm tile, laminate, or concrete flooring
• Heat concentrated in one area of the home
• Floors that feel warm even when water is not in use

High Gas or Energy Bills

A hot water slab leak can cause water heaters to run continuously, leading to higher gas or energy bills without any change in usage.

• Sudden increase in gas or energy bills
• Water heater running more frequently than normal
• Hot water running out faster than usual

Floor and Foundation Damage

Ongoing water movement beneath the slab can weaken flooring materials and the foundation itself.

• Cracked tiles or lifting flooring
• Soft or warped floors
• Cracks forming in the slab or foundation

Ants or Insects Appearing Indoors

Moisture from a slab leak can attract ants and other insects. A sudden increase in ants throughout the house may indicate water beneath the slab.

• Ant trails appearing with no visible food source
• Insects concentrated near floors or walls
• Recurring pest activity despite treatment

Mold and Odor Issues

Water trapped under flooring or behind walls can create conditions for mold growth and unpleasant odors.

• Musty smells with no visible leak
• Mold near baseboards or flooring edges
• Persistent indoor humidity

What to Do If You Notice These Signs

If one or more of these warning signs are present, a professional slab leak inspection is recommended. Early detection allows for accurate diagnosis and helps determine whether targeted repair or full repiping is the best solution.