Underground water leaks are often silent threats. Since the pipes are hidden beneath your lawn, driveway, or foundation, they can go unnoticed until major damage has already occurred. Recognizing the signs early can save you thousands of dollars in repairs and water bills. Here’s how to identify and confirm an underground leak—and what to do next.

Why Underground Leaks Are Serious

Underground leaks may seem minor, but over time they can:

• Weaken your home’s foundation

• Cause sinkholes or water damage in the yard

• Lead to mold and mildew indoors

• Significantly increase water bills

• Waste hundreds of gallons of water every day

Because they’re out of sight, underground leaks are harder to detect and require specialized tools or professional help. Ignoring them can result in major property damage and plumbing emergencies.

Common Signs of an Underground Water Leak

Unexplained Increase in Water Bills

If your water usage hasn’t changed but your bill spikes, it may point to a hidden leak—especially if you’re already practicing good plumbing maintenance habits.

Wet Spots or Muddy Areas in the Yard

Patches of lawn that are unusually soggy, muddy, or greener than surrounding areas could be above a leaking pipe.

Cracks in Foundation or Driveway

Water leaking beneath your home can shift the soil, leading to cracks in your slab foundation, basement walls, or concrete driveway.

Low Water Pressure Indoors

If faucets and showers start running weak, especially in combination with outdoor symptoms, the leak may be affecting water flow.

Sound of Running Water When Fixtures Are Off

Can you hear water hissing, dripping, or flowing even when everything is turned off? This is a strong indication of a hidden leak.

Mold or Mildew Smells Indoors

Persistent dampness or musty smells inside your home could signal water seeping upward from an underground source.

How to Confirm a Water Leak Underground

Check the Water Meter for Movement

Turn off all water in the house and watch the meter. If it continues to spin, water is flowing somewhere—possibly underground.

Perform a Meter Leak Test

• Record your water meter reading.

• Wait 2 hours without using water.

• Recheck the meter.
  If the number increases, there’s a leak in your system.

Shut Off Valves and Recheck Pressure

Shut off valves to specific parts of your home and recheck for pressure changes or meter movement. This can help isolate the leak’s location.

Use Leak Detection Tools or Hire a Specialist

Thermal imaging, acoustic sensors, and pressure testing are professional methods used to locate underground leaks accurately. Our team at WoWorld offers licensed leak detection services for residential and commercial properties.

What to Do If You Suspect an Underground Leak

Turn Off Main Water Supply

Minimize damage by shutting off the main valve until the leak is located and repaired. Learn how in our shut-off valve guide.

Call a Licensed Plumber or Leak Detection Service

Underground leaks aren’t DIY-friendly. You’ll need an expert with the right tools and permits to dig safely and perform repairs without further damage.

Avoid Digging Without Utility Marking

Never dig without contacting local authorities or utility companies for line marking. Damaging a gas or power line can be dangerous and illegal.

Preventing Future Underground Leaks

• Schedule routine plumbing inspections

• Use quality, corrosion-resistant piping materials

• Avoid planting deep-rooted trees near water lines

• Install pressure-reducing valves if you live in high-pressure areas

• Winterize pipes to avoid freezing and expansion-related bursts

Proactive maintenance and timely repairs are the best defenses against hidden water damage.