The short answer
A toilet that runs full time in Northern Virginia can waste over 1,000 gallons a day, by Fairfax Water’s own count. Over a three-month billing quarter in Fairfax County, that’s about $1,294.93 with sewer, or $395.85 in a quarter when sewer is capped. A slow, silent flapper leak is smaller, and it still adds up because you only see a bill every three months. Most of the time the fix is a flapper or a fill valve, not a new toilet.
What leaks cost in a quarter
These use Fairfax County’s numbers: $4.35 per 1,000 gallons for water from Fairfax Water, plus $9.88 per 1,000 for county sewer when sewer applies. Sewer applies to every gallon in the winter quarter (the February to April reads). The rest of the year it’s capped at your winter level, so leaked gallons are mostly water only.
Swipe to see all columns →
Swipe to see all columns →
| The leak | Gallons a quarter | Winter quarter, water and sewer | Rest of the year, water only |
|---|---|---|---|
| A faucet dripping once a second EPA: more than 3,000 gallons a year |
750 | $10.67 | $3.26 |
| A small leak, 50 gallons a day EPA: 9% of homes leak this much or more |
4,550 | $64.75 | $19.79 |
| A bigger leak, 90 gallons a day EPA: 5% to 10% of homes |
8,190 | $116.54 | $35.63 |
| A 1/32 inch hole in an irrigation line EPA: about 6,300 gallons a month |
18,900 | Usually off in winter | $82.21 |
| A toilet running full time Fairfax Water: over 1,000 gallons a day |
91,000 | $1,294.93 | $395.85 |
One catch in summer: on bills that end June through November, Fairfax Water adds a $4.20 peak charge per 1,000 gallons on use well over your winter level, so a big leak then costs more than the last column.
Even one week of a toilet running full time is about 7,000 gallons, close to $100 in the winter quarter. And a faucet that drips is small money on its own, but it’s rarely the only thing dripping. The EPA puts the average household’s leaks at more than 9,300 gallons a year.
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Why it gets so big before you notice
Northern Virginia water bills come every three months. Fairfax Water, Loudoun Water, Arlington and Vienna all bill by the quarter. A toilet that starts running the week after the meter is read can run for twelve weeks before the bill shows up. Prince William Water bills monthly, which helps, but a month is still a lot of water.
In Loudoun it climbs faster. Loudoun Water charges $3.37 per 1,000 gallons for the first 25,000 gallons in a quarter, $9.34 for the next 25,000, and $12.52 past 50,000. A leak doesn’t just add gallons. It pushes them into the pricier tiers. Arlington works the same way: $4.73 per 1,000 gallons, $7.57 once you pass 9,000 gallons in a quarter, plus $10.48 for sewer.
Signs your toilet is running
- It refills by itself every so often with nobody near it. Plumbers call that a phantom flush.
- A hiss or a trickle you can hear from the hallway at night.
- Water running into the overflow tube in the middle of the tank.
- The handle has to be jiggled to make it stop.
- Food coloring in the tank shows up in the bowl within ten minutes without a flush. That’s the EPA’s dye test, and a worn flapper is the usual reason.
The fixes, from free to a new toilet
Adjust the fill level. If water is spilling into the overflow tube, the float is set too high. Turn the screw on top of the fill valve or slide the float clip down until the water stops about an inch under the top of the tube.
Replace the flapper. Rubber flappers warp and stiffen after a few years, especially with tank cleaning tablets. Shut the valve behind the toilet, flush to drain the tank, unhook the old flapper and match the new one to the size of the opening. Bring the old one to the store.
Replace the fill valve. If it hisses, refills slowly, or won’t shut off, the fill valve is done. Toilet keeps running and the running toilet guide walk through both.
Replace the toilet. If it’s cracked, rocks on the floor, or it’s an old one that uses a lot per flush, a new one pays you back.
Is it the flushes?
It can be. Older toilets use as much as 6 gallons per flush. Federal law has held new toilets to 1.6 gallons since the 1990s, and WaterSense models use 1.28 or less. Look for a number stamped behind the seat hinge or inside the tank. For every 1,000 flushes, a 6 gallon toilet uses 6,000 gallons and a 1.28 gallon toilet uses 1,280. In Fairfax County’s winter quarter that difference is about 7 cents a flush, and a busy house flushes a lot.
We take $100 off replacing a toilet, any brand, any bathroom in the house. The code is on our offers page, and what a new toilet costs has the rest.
When it isn’t the toilet
If every toilet passes the dye test and the bill is still high, the meter test comes next: no water for two hours, read the meter before and after, and if it moved, you have a leak somewhere. Why is my water bill so high lists where they hide, from the irrigation to the softener to the line under the yard.
Get some of it back
Most local utilities give a one-time or once-every-few-years credit for a leak you fixed, and they want proof of the repair. Keep the receipt or the plumber’s invoice. How to get a water bill leak adjustment has each utility’s rules. Irrigation and water left running usually don’t qualify. A broken toilet part does.
Our Water Test and Plumbing Safety Check is $29: a licensed plumber walks your plumbing with photos, checks the water heater and tests your water’s hardness at the kitchen table. Hand them the bill and tell them what’s been running. If you already know something’s leaking, a plumbing visit is $49 in regular hours, and the price of the fix is in writing before we start. Booking a plumbing repair? The whole-house plumbing inspection comes with it, so the next drip gets caught too.
Get a plumber on it
Book a plumber online, call (703) 997-9757, or book the $29 plumbing safety check. We answer day or night. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
How much does a running toilet add to a water bill?
A toilet running full time can waste over 1,000 gallons a day. Over a quarter in Fairfax County that’s about $1,294.93 with sewer in the winter quarter, or $395.85 water only. A slow flapper leak costs less but runs until you fix it.
How do I know if my toilet is leaking?
Put a few drops of food coloring in the tank and don’t flush for ten minutes. If color shows up in the bowl, the flapper is leaking. A toilet that refills on its own or hisses is leaking too.
Do old toilets use more water?
Yes. Older toilets can use as much as 6 gallons per flush. New toilets are held to 1.6 gallons, and WaterSense models use 1.28 or less.
Will the water company credit me for a running toilet?
Usually once. Fairfax Water gives one courtesy leak adjustment every five years with proof of repair, and Loudoun Water gives one per account for a leak inside the house. Keep your receipt or invoice.
