Start with the meter test
This ten-minute check tells you definitively whether you have a leak:
- Turn off every faucet and fixture, and make sure no appliance (dishwasher, washing machine, ice maker, irrigation) is running.
- Find your water meter — in most Northern Virginia homes it’s in a ground-level box near the street or sidewalk.
- Watch the small low-flow indicator (usually a small triangle or star on the dial). If it’s turning with everything off, water is moving through the meter — you have a leak.
- To narrow it down, close the home’s main shutoff valve and look again: if the indicator stops, the leak is inside the house or in irrigation past the valve; if it keeps moving, the leak is in the underground service line between the meter and the house.
Check the toilets first — the #1 offender
A toilet with a worn flapper or misadjusted fill valve runs silently and can waste more water than every other fixture combined. Two quick tests:
- The dye test: put a few drops of food coloring in the tank, wait 15–20 minutes without flushing. Color in the bowl means the flapper is leaking.
- The listen test: if you ever hear a toilet refill on its own when nobody has flushed (“phantom flushing”), the tank is leaking into the bowl.
Flappers and fill valves are inexpensive parts — this is the cheapest high-water-bill fix there is.
Where hidden leaks hide
- Slab leaks: a supply line leaking under the concrete slab. Clues: warm spots on the floor, the sound of running water with everything off, or a water heater that runs constantly.
- Underground service line: the pipe from the meter to the house. Clues: a soggy or unusually green strip of lawn along the pipe’s path.
- Behind walls and ceilings: pinhole leaks in older copper. Clues: stains, bubbling paint, musty smell, or a spongy floor.
- Outdoors: irrigation zones, a hose bib that drips after use, or a frost-damaged spigot that leaks inside the wall when running.
- Water softener or humidifier stuck in a regeneration/fill cycle, quietly sending water down the drain around the clock.
Rule out the boring explanations too
Before hunting for a leak, check whether the bill itself explains it: seasonal irrigation starting up, house guests, a rate increase, or an estimated-vs-actual meter reading catching up. Fairfax Water and other Northern Virginia utilities show usage history on your bill — a gradual climb suggests habits or rates; a sudden spike with no lifestyle change suggests a leak.
When to bring in leak detection
If the meter test says “leak” but the toilets pass and nothing is visibly wet, that’s when professional leak detection earns its keep — acoustic listening and other non-invasive tools locate the leak before anyone cuts drywall or concrete, so the repair opens exactly the right spot. Waiting is the expensive option: water finds drywall, flooring, and framing long before it becomes visible.
High water bill and can’t find the cause? We locate and fix hidden leaks across Northern Virginia, with an upfront quote before any work. Call (703) 832-9090 or see our leak & repair service.