Detecting Leaks

High Water Use Alert

If you received a notice about "High Water Use Alert," that means our team member noticed an increase in usage while reading your meter. You may be expecting this increase; if not, check for the following common causes of leaks.

Check for Leaks: Toilet

Leaky toilets are the most common source of a leak. All you need is food dye or dye tablets, which Fairfax Water provides at its office in Merrifield (8570 Executive Park Avenue) during business hours (Monday through Friday, 8am to 6pm). Test every toilet in your home. (Download a printable flyer here in English and Spanish.)

  1. Flush your toilet.
  2. Wait five minutes. Remove the tank lid (see picture below).
      Picture pointing to the lid of the toilet tank. The tank is the highest part of the toilet, above the bowl.
  3. Place five drops of red or blue food dye or one color dye tablet into the tank. Do not flush.
  4. Wait 15 minutes. If dye appears in the bowl, you have a leak.

Common Reasons for Toilet Leaks

See picture below to help determine what issue your toilet may have that is causing the leak. (Download a printable flyer here in English and Spanish.)

Diagram showing four parts of a toilet tank. A shows the flapper valve. B shows the flushing arm. C shows the overflow tube. D shows the float rod and ballcock.
  1. The flapper valve may have deteriorated.
  2. The flushing arm and lift chain might be malfunctioning.
  3. The water level in the tank might be too high and spilling into the overflow tube.
  4. The float rod, ballcock or float ball might be corroded.

To make repairs, find replacement parts at hardware stores or hire a plumber. Fairfax Water does not provide plumber recommendations.

Check for Leaks: Water Meter

If you have access to your meter box, one way to detect a leak is to read the water meter.

  1. Turn off all faucets and running water.
  2. Go to your water meter and note the current gallon count.
  3. Wait at least 15 minutes without using any water.
  4. Read the meter again. If the numbers have changed, you may have a leak.
  5. You can also wait longer between meter readings, like reading the meter before you go to bed then as soon as you wake up, before using any water. This might help you detect slow or intermittent leaks.

Check for Leaks: Underground

If there appear to be no leaks inside your home, and the meter is located outside, check for underground leaks.

  1. Turn off your main valve inside, then open a faucet to verify that the valve is working. The water flow should stop completely.
  2. Go back outside to the meter to see if it continues to run with the main valve off. If it does, there is a leak somewhere in your plumbing between the meter and the valve.

Help with Your Bill after a Leak

As a courtesy, we offer a one-time adjustment for unusually high water charges caused by leaks. Please note all the details regarding adjustments are within the Rules and Regulations, under the section Courtesy Leak Adjustments.

To be eligible for adjustment, the Customer must do all of the following:

  1. Promptly and properly repair the leak when detected;
  2. Provide written proof of repairs to Fairfax Water through copies of receipts or an invoice; and
  3. Not have received a Courtesy Leak Adjustment from Fairfax Water during the previous five years.

Please use the Leak Adjustment Request Form to submit the required information.

Email, mail, or fax the completed form to:

  • Email: Customer Service
  • Mail to:
    Fairfax Water
    Attn: Billing
    8570 Executive Park Avenue
    Fairfax, VA 22031
  • Fax: 703.289.6133

Once we receive the necessary information, we will notify you within four weeks if an adjustment has been approved. Only one quarterly billing period will be adjusted at a $5,000 capped amount. Additional information can be found on the Rules and Regulations webpage.