Underground Leak Detection

Hi Everyone, welcome back to Happi Plumbing Channel. Today we will see an interesting underground leaking detection case from Happi Plumbing.

The customer is concerned that “I have a leak in the main supply line to my house, with a flow of about 1.5 gallons per minute. I need either leak detection and repair, or a trenchless line replacement.”

1.5 gallons per minute is basically one full bucket of water every 4 minutes.

Step 1: Diagnose and locate the general leak area

The customer had an underground water line leak more than a month ago. A plumbing company broke the concrete and repaired part of the underground pipe. Now the leak has returned, so the customer was considering replacing the entire underground line.

Using a process of shutting off valves one by one, we isolated the issue to this specific valve. When the valve was closed, the water meter stopped spinning, which means the leak is somewhere behind this valve.

Following the pipe, we discovered that this line is actually the pool supply line.

Step 2: Pressurize the system with air and locate the leak using Sonar equipment

In the crawlspace, right behind this valve, there is a backflow preventer.
We injected high-pressure air into the system through the test cock.

Then we followed the underground route of the pool supply pipe and used Sonar leak-detection equipment to listen for the leak location.

Eventually, we identified the leak at the pool fill valve.

Step 3: Repair

By adjusting the fill valve, the leak stopped. However, we advised the customer to purchase a new valve soon for full replacement.

The customer was originally planning to replace the entire underground line, but it turned out unnecessary — and the customer was very HAPPY!