Water & Sewer Lines
How to Use the Water Meter Leak Indicator to Find a Leak
Your water meter is the cheapest leak detector you own. Most homeowners never look at it, but a two-minute check can confirm whether you have a hidden leak and roughly where it is. This guide shows how. If the test points to the buried line between the meter and your house, our team handles water line repair in McLean and can find the exact spot before digging.
Where is my water meter?
In much of McLean and Fairfax County, the meter sits in a small pit near the street or property line, covered by a round metal lid. Some homes have the meter inside, usually in the basement where the water line enters. An archived Fairfax Water page notes that for inside meters, Fairfax Water maintains only the meter and its remote reader. If you are a Town of Vienna customer, the town handles the meter.
Use a screwdriver to lift the lid carefully. Watch for insects and do not reach in blind. Some meters have a protective cap you can flip open.
How do I read the leak indicator?
Most meters have two parts:
| Part | What it shows |
|---|---|
| Main register | Total water used, like a car's odometer |
| Sweep hand or digital flow rate | Water flowing right now |
| Leak indicator (triangle, star, gear or small dial) | Very low flow, even a slow drip |
If the leak indicator turns when nothing in the house is using water, you have a leak.
How do I do the meter leak test?
- Turn everything off. Faucets, showers, toilets (no flushing), dishwasher, washing machine, ice maker, water softener regeneration and irrigation.
- Watch the leak indicator for a few minutes. Any movement means water is flowing.
- For slow leaks, use the two-hour test. Write down the meter reading, wait two hours without using water, and read it again. The EPA recommends this method.
- Note the result. If the reading changed, you have a leak.
Is the leak inside the house or in the yard?
Next, find your main shutoff valve. In most McLean homes it is in the basement where the water line comes through the wall.
- Close the main shutoff.
- Watch the meter again.
- If the meter still moves, the leak is likely in the buried service line between the meter and the house.
- If the meter stops, the leak is inside the house.
Fairfax County's health department says homeowners are responsible for the water line into the house starting from the street lateral. So an outside leak is usually a private repair. Our guide on who owns the water line explains the details.
What are the most common indoor leaks?
Before assuming a hidden leak, check the usual suspects:
- Toilets. Put food coloring in each tank. Color in the bowl within 10 minutes means the flapper leaks.
- Faucets and showerheads. Look for drips. The EPA says a faucet dripping once per second wastes more than 3,000 gallons a year.
- Water heater. Check the relief valve discharge pipe and the base of the tank.
- Water softener. It may be stuck in a cycle.
- Outdoor hose bibs and irrigation. A stuck valve can run all day.
How much water can a leak waste?
The EPA's WaterSense program says the average home's leaks can waste more than 9,300 gallons a year, and nine percent of homes have leaks that waste 50 gallons or more a day. A hidden supply line leak runs 24 hours a day, so it can be far worse than a drip.
What if I am on a well?
Homes on private wells do not have a utility meter. Instead, watch the well pump. If it turns on when no one is using water, or the pressure gauge drops steadily, you may have a leak. We can check well systems too.
How often should I check my meter?
Once a month is a good habit, and any time your bill jumps. It takes two minutes and can catch a leak before it causes damage.
Local note: Large lots in Great Falls may have long service lines and irrigation, and some homes there use wells instead of meters. In Vienna, many homes are Town of Vienna customers. In Tysons condos, units may not have their own meter, so watch for stains and sounds instead.
Related reading: See what sets leak detection cost, learn what a slab leak is, and read about pinhole leaks in copper pipes.
When should you call a plumber?
Call when the meter moves with everything off and you cannot find a running toilet or drip, when the meter keeps moving after you close the main valve, or when you see wet ground over the water line.
Meter test shows a leak in McLean? Call (571) 760-4451 for leak detection and water line repair from McLean Plumber Works.
Frequently asked questions
What is the leak indicator on a water meter?
It is a small triangle, star, gear or dial on the meter face that spins with very low flow. If it moves when no water is being used, water is escaping somewhere past the meter.
How long should I wait during a meter test?
The EPA suggests reading the meter, waiting two hours with no water use, and reading it again. A leak indicator can show movement in just a few minutes.
Where is my water meter in McLean?
Many Fairfax Water meters sit in a pit with a metal lid near the street or property line. Some homes have the meter inside, often in the basement where the line enters.
My meter moves but I can't find a leak. What next?
Close the main shutoff valve in the house and watch the meter again. If it still moves, the leak is likely in the buried line. If it stops, the leak is inside the home.
Can a running toilet move the meter?
Yes. A worn flapper is one of the most common reasons a meter moves. Do a dye test on each toilet before assuming the leak is hidden.
Sources
Related guides
Meter moving with everything off? Call for help.
Call McLean Plumber Works any time, day or night. A plumber picks up and talks you through next steps.