Using Your Water Meter to Test for Sprinkler Leaks

Your water meter is the best leak detector you already own. With a few minutes and a little patience, it can tell you whether water is leaking at all, and whether the leak is in the sprinkler system, the house or the line between them. This article explains how to find the meter, read it and run a simple test.

Finding and Opening the Meter Box

In most Fort Worth neighborhoods, the meter sits in a concrete or plastic box near the street, often close to the property line or the edge of the driveway. The lid may be marked “Water.” Lift it with a screwdriver or meter key. Watch for insects, spiders and standing water inside, and do not reach in blindly.

If the meter face is dirty or fogged, gently wipe it off. Do not force the meter lid or try to adjust anything inside. The meter belongs to the utility.

Reading the Meter

Most residential meters have three things you care about:

• The main number display, which shows total water used, usually in gallons or cubic feet.
• The sweep hand or digital flow display, which shows smaller amounts as they pass.
• The leak indicator, often a small red or black triangle or star that spins when even a small amount of water flows.

The leak indicator is the key part for this test. If it moves when all water use is off, water is flowing somewhere.

Step 1: Stop All Water Use

Make sure nothing is using water:

1. Turn off all faucets, showers and hose bibs.
2. Make sure the dishwasher, washing machine, ice maker and water softener are not running.
3. Confirm the sprinkler controller is not in the middle of a cycle. Setting it to off for the test is easiest.
4. Ask everyone in the house not to use water for the next half hour.

Step 2: Watch the Leak Indicator

Look at the leak indicator for a full minute or two. If it does not move, write down the numbers on the main display. Wait 15 to 30 minutes without using any water, then look again. If the numbers changed, there is a slow leak. If the indicator was already spinning in step 2, you have a larger leak.

Step 3: Isolate the Irrigation System

Find the irrigation isolation valve. It is usually between the meter and the backflow preventer, sometimes in its own small box, sometimes right at the backflow preventer. Close it. If you cannot find a separate valve, close the shutoff valve on the inlet side of the backflow preventer.

Now watch the leak indicator again:

• If it stops, the leak is on the irrigation side, most likely the mainline, a valve or the backflow preventer.
• If it keeps moving, the leak is in the house plumbing or on the service line between the meter and the house.

Step 4: Narrow It Down on the Irrigation Side

If the leak is on the irrigation side, look at the backflow preventer first for drips or spraying. Then walk the path of the mainline, usually from the backflow preventer toward the valve boxes, looking for soggy spots. Open each valve box and look and listen. Our articles on signs of a hidden sprinkler leak and a leaking backflow preventer cover what you may find.

Keep the irrigation isolation valve closed until the leak is repaired. You can open it briefly to water on your assigned day if the lawn needs it, but the leak will run during that time too.

What the Meter Test Will Not Show

This test finds leaks in pipe that is always under pressure. It will not find leaks in lateral lines, because those only hold water when their zone runs. To find a lateral leak, run each zone and watch for bubbling, pooling, weak heads or a small fountain. Our zone-by-zone system check is the right tool for that.

It also will not catch a valve that only sticks open sometimes. If you suspect that, check the yard early in the morning after a watering cycle for zones that are much wetter than others. Our guide on a zone that will not turn off explains what to look for.

Using the Meter to Measure Zone Flow

The meter can also tell you roughly how much water each zone uses. With nothing else running, note the reading, run one zone for exactly five minutes, and note the reading again. Divide the difference by five for gallons per minute. Doing this for each zone gives you a baseline. If a zone later uses a lot more water than its baseline, something on that zone is leaking or broken.

Checking the Meter Before and After a Repair

The meter is also a good way to confirm a repair worked. Once a leak is fixed and the system is back on, repeat the test: stop all water use, open the irrigation isolation valve, and watch the leak indicator. If it stays still, the leak is gone. It is worth doing the same test again a week later, since some repairs, such as a glue joint that was not quite right, only start leaking again after a few pressure cycles. Writing down the date and result each time gives you a simple history to look back on.

When to Call for Help

If the meter test shows a leak on the irrigation side and you cannot find it, or it points to a mainline leak, a technician can locate and repair it. If the test points to the house, a plumber is the right call. For high bills in general, see our guide on high water bills and sprinkler leaks, and for the repair itself, our sprinkler repair service.