Find the meter and read it
In a Philadelphia house with a basement, PWD says the meter usually sits against the basement wall closest to the street, anywhere from ankle to chest height. In converted homes it can be in a crawl space or behind a wall; following the incoming pipe helps. EPA notes that in many other places the meter is in a covered box near the curb. If yours is outside and you can't open the lid easily, or you can't reach it safely, ask your water utility to help rather than forcing it. In Bucks County, start by finding out who your water provider is.
On a PWD meter, the six-digit register shows usage: the first four digits are what you're billed on, in units of 100 cubic feet, and the two shaded digits show smaller amounts. The red sweep arm goes around once per cubic foot. The small blue dial is the leak indicator: PWD says it moves whenever any water flows through the meter, so even a tiny leak will turn it. Don't mix up the meter's ID number, which is stamped on the brass outlet and printed on a sticker, with the reading.
Run the test
- Pick a time when nobody needs water for two hours. Turn off or wait out anything automatic: dishwasher or washer cycles, an ice maker, a water softener, irrigation, a humidifier.
- Check the blue leak dial first. If it's moving with everything off, you already have your answer.
- Write down or photograph the full register and the time. Two hours later, read it again. EPA's guidance is that if it changed at all, you probably have a leak.
- If someone ran water during the test, start over instead of counting the difference.
A bill can point the same way. EPA says that in a home with no outdoor watering in winter, a family of four using more than 12,000 gallons a month in January or February likely has a serious leak.
Check every toilet separately
EPA lists worn toilet flappers among the most common household leaks, and they make no noise. Do this as its own test, since the final flush moves the meter. Put a few drops of food coloring or a dye tablet in the tank (not the bowl) and wait 10 minutes without flushing. Color in the bowl means water is leaking from the tank past the flapper or flush valve seal. EPA says that's usually fixed by replacing the flapper, not the toilet, and PWD notes flappers are inexpensive. Flush afterward so the dye doesn't stain, and don't skip a basement or rarely used toilet.
Narrow it down
- Meter moving and a toilet failed the dye test: fix the toilet, then repeat the meter test. You may have more than one leak.
- Meter moving but every toilet passed: check faucets in the kitchen, baths, laundry and basement, showerheads, and outdoor spigots, and look under sinks for puddles. Our guide to a slow leak under the kitchen sink helps tell a supply leak from a drain leak. PWD's advice for a puddle under a sink is to close that fixture's shutoff valve and call a plumber.
- Meter moving and nothing inside explains it: the leak may be in a pipe you can't see, including the line between the street and your meter. Don't open walls or dig based on the meter alone; have a plumber locate it first.
- Meter didn't move: nothing leaked during those two hours. If bills stay high, repeat the test at a different time of day.
Who fixes it in Philadelphia
PWD is responsible for the water main and sewer main only. Its leak page says the property owner is responsible for leaks from the connection at the main all the way through the property, and for the costs those leaks cause. PWD can't confirm a leak inside your home or repair it. Our guide on who pays to fix a leaking water service line covers the outside part in more detail. PWD points to the Department of Licenses and Inspections' contractor search for finding a licensed plumber.
When you call a plumber, have your meter photos, test times and the reading difference, and your dye test results ready. Ask which lines or fixtures they'll check first, how they'll pinpoint the leak before cutting into anything, and how they'll confirm afterward that the meter has stopped moving. If water is actively pooling or dripping through a ceiling, shut off the main valve and call right away instead of running a two-hour test.