The short answer
A dripping faucet can waste anywhere from a few gallons a month to several thousand gallons a year, depending on how fast it drips. Drip size varies, so any number is an estimate. Using the USGS estimate of 1/4 milliliter per drip, a faucet dripping once per second wastes about 2,000 gallons a year, which is why even a slow drip is worth fixing.
Approximate waste by drip rate
These figures are calculated from the USGS estimate of 1/4 milliliter per drip (about 15,140 drips per gallon). Real drips vary in size, so treat them as rough guides, not exact measurements.
| Drip rate | Approximate waste per day | Approximate waste per year |
|---|---|---|
| About 10 drips per minute | Around 1 gallon | About 350 gallons |
| One drip every 2 seconds | Close to 3 gallons | About 1,000 gallons |
| One drip per second | Roughly 6 gallons | About 2,000 gallons |
| A thin steady stream | Many gallons | Can reach tens of thousands of gallons |
Hot-water drips also waste the energy used to heat the water.
Measure your own drip
You can get a better estimate for your own faucet in a few minutes.
- Place a measuring cup or small container under the drip.
- Time it for a set period, such as 10 minutes.
- Measure the water collected, then scale it up: multiply by 6 for an hourly figure, or by 144 for a daily figure.
- Convert the result to gallons or liters as needed.
Water utilities and some government agencies publish online drip calculators if you prefer to count drips per minute instead.
What a drip costs you
The cost depends on your local water and sewer rates, and on whether the water is heated. To estimate it, find the price per gallon or per 1,000 gallons on your water bill, then multiply by your daily waste figure. For many households, one drip is a small amount per month. The bigger risks are that the cause may worsen, that several fixtures may be dripping, and that a drip may signal high water pressure or worn parts.
Leaks that waste more than a faucet
Faucets are rarely the biggest source of waste in a home. Others to check:
- Toilets. A leaking flapper can lose a large amount of water without any visible drip or noise. A running toilet (see can a leaking toilet cause a high water bill) can waste far more than a dripping faucet, and a severe case can lose many gallons per hour. Whether one reaches 100 gallons an hour depends on the fault, but a toilet that continuously refills is worth fixing promptly. A food coloring test in the tank, left without flushing, shows whether it leaks into the bowl.
- Showerheads and hose bibs. Drips here are easy to miss.
- Irrigation systems and outdoor spigots, which can leak when no one is looking.
- Hidden leaks in pipes, which can waste water for a long time. Run the meter test described in signs of a leaking pipe.
As for what wastes the most water in a typical home, outdoor irrigation, toilets and long showers tend to be large users, and leaks can add significantly to the total. Your own bill and meter are the best guide.
Why faucets drip
Common causes include:
- A worn washer or O-ring in a compression faucet
- A worn cartridge, ball or seat in a washerless faucet
- Mineral buildup or a corroded valve seat
- Loose parts
- High water pressure, which can cause several fixtures to drip or wear out sooner
If more than one faucet drips, or you hear banging pipes, ask a plumber to check the water pressure.
Fix it or replace it?
Many drips come from an inexpensive part. Before you start:
- Shut off the water at the fixture’s shutoff valves under the sink, or at the main if there are none. Open the faucet to release pressure.
- Plug the drain and place a towel in the sink so small parts do not fall in.
- Identify the faucet type and look up the model, so you can buy the right replacement parts.
- Replace the worn part, then reassemble and test.
Replacing the faucet may make more sense if it is old, heavily corroded, hard to get parts for, or has dripped again after repairs.
When to call a plumber
- The shutoff valves will not close or leak themselves
- The drip comes from the base of the faucet or from the supply lines, not the spout
- Corrosion or damage has spread to the sink, countertop or cabinet
- Several fixtures drip, or water pressure seems high
- You are unsure about opening the faucet or the leak continues after a repair
- Your meter shows flow even when all fixtures are off, which suggests a leak elsewhere in the house
For the full picture of other leak symptoms, see signs of a leaking pipe.