Pipes & water supply

Main water line leak in the yard

A wet spot in the yard along with a rising water bill often points to a leak in the underground service line between the meter and the house, which needs professional locating and repair.

Difficulty
Professional only
Time
1–3 days including detection and repair
DIY cost
N/A
Pro cost
$500–$4000+

Symptoms

  • Unusually soggy or lush patch of grass with no other explanation
  • Sound of running water audible near the ground when everything indoors is off
  • Water meter shows movement with all fixtures off
  • Water pressure inside the house may have dropped slightly

Likely causes

  • CommonCorrosion or age-related failure of the underground service lineBuried pipe, especially older galvanized or thin-walled copper, can develop leaks after decades underground.
  • CommonGround shifting or tree root intrusion damaging the lineRoot growth or soil movement can crack or crush buried pipe over time.
  • PossibleDamage from recent digging or landscaping workA leak that appeared suddenly after yard work often traces back to accidental pipe damage during that work.
  • Less commonFreeze damage to a shallowly buried linePipe buried above the frost line in a particularly cold winter can crack from freezing.

What to do

  1. Confirm an active leak using the water meter test: turn off all fixtures and watch for meter movement over 15–30 minutes.
  2. Look for the wettest or most vibrant grass along the likely path between the street connection and the house.
  3. Call 811 (or your local utility locate service) before any digging to have all underground utility lines marked, which is often free and required by law.
  4. Contact a licensed plumber for professional leak detection to pinpoint the exact location before digging, since guessing can lead to unnecessary yard damage.
  5. Depending on the leak's severity and location, repair options include patching the specific damaged section or replacing the entire service line.
  6. Check whether your water utility or a service line insurance program covers repair costs, since some municipalities offer this.
  7. After repair, monitor your next water bill and meter readings to confirm the leak is fully resolved.

Tools and parts

  • None (professional detection recommended)

When to call a pro

Call a licensed plumber for professional leak detection and repair of the main service line; always call 811 before any digging.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.