Plumbing · Lesson 8 of 13Beginner7 min read

Leaks and Water Use

A drip doesn’t look like much. But EPA says the average household’s leaks can waste more than 9,300 gallons a year, and nationwide household leaks waste nearly a trillion gallons. Finding them takes two free tests and a little detective work.

How much leaks waste

EPA’s WaterSense program has the numbers:

The average household’s leaks can waste more than 9,300 gallons a year.
Nine percent of homes have leaks that waste 50 gallons or more a day.
A faucet dripping once a second can waste more than 3,000 gallons a year.
A showerhead leaking 10 drips a minute wastes more than 500 gallons a year.
A worn toilet flapper can silently leak thousands of gallons a year, and EPA’s septic program says a single running toilet can waste up to 200 gallons a day.
Fixing easily corrected leaks can save about 10 percent on water bills.

The counter below turns drips into gallons and dollars. EPA’s two faucet and showerhead figures both work out to drops of about 0.36 milliliter, so that’s where the drop size starts.

Set your own water price from your bill. Drop size varies with the faucet; the default matches EPA’s figures.

gallons per year = drips per minute × 525,600 minutes × drop size (mL) ÷ 3,785.4 mL per gallon
60 drips/min × 525,600 × 0.36 mL ÷ 3,785.4 ≈ 3,000 gallons

The two-hour meter test

Your water meter is the best leak detector you have. EPA says it’s usually underground near the curb, though it may be indoors, such as in a basement. Read it, use no water at all for two hours, and read it again. If the reading changed at all, you probably have a leak somewhere.

Your winter bill is another clue. EPA says a family of four that uses more than 12,000 gallons a month in winter, when there’s no outdoor watering, probably has a serious leak. Bills often measure water in hundreds of cubic feet, or CCF. A cubic foot is exactly 0.3048 meter cubed and a gallon is 3.785412 liters, so one CCF is about 748 gallons, and EPA’s 12,000 gallons is about 16 CCF. A bill much higher than the same month last year can also point to a leak you haven’t found.

EPA’s test: read the meter, use no water for two hours, and read it again. If it changed at all, you probably have a leak. Meters differ; some read in cubic feet.

1 CCF = 100 ft³ × 28.317 L per ft³ ÷ 3.785 L per gallon ≈ 748 gallons

The toilet dye test

Toilets are common silent leakers. EPA’s test: put a few drops of food coloring or a dye tablet in the tank, don’t flush, and wait 10 minutes. If color shows up in the bowl, water is leaking past the flapper. Flush afterward so the dye doesn’t stain. EPA suggests replacing flappers at least once every five years. Fix a Running Toilet covers the fixes, and Lesson 4 has an animated toilet with the common faults.

Finding hidden leaks

If the meter says there’s a leak and the toilets pass the dye test, go hunting:

Under sinks and behind appliances: look for drips at pipe connections, puddles and water spots, as EPA suggests. Check supply lines to toilets, faucets, the dishwasher, the refrigerator ice maker and the clothes washer.
Faucets and showerheads: EPA notes that leaky faucets can often be fixed by replacing worn washers and gaskets, and a dripping showerhead by tightening its connection with pipe tape and a wrench.
The water heater: look for leaks, aged gaskets, loose connections and corrosion, and water at the T&P valve’s discharge pipe.
Outdoors: check the garden hose connection and its rubber washer. EPA’s older leak guide says an irrigation leak only 1/32 of an inch across can waste about 6,300 gallons a month.
Ceilings, walls and floors: stains, bubbling paint, warped flooring and musty smells can mark a leak inside a wall or ceiling.

EPA’s campus guide suggests a simple measurement: set a container under a drip for an hour and see how much it holds. Then you know your real leak rate.

Where the water goes, and using less

Toilets are nearly 30 percent of an average home’s indoor water use and showering nearly 17 percent, according to EPA. EPA’s septic program puts typical indoor use as high as 70 gallons per person per day in a single-family home. WaterSense labeled fixtures are independently certified to use less while still working well: EPA estimates a family can save nearly 13,000 gallons a year by replacing old toilets, 2,700 gallons a year with WaterSense showerheads and 700 gallons a year with WaterSense bathroom faucets.

EPA gives “nearly 30 percent” for toilets and “nearly 17 percent” for showering. The rest is not broken out here.

You canYou can do both tests today

The two-hour meter test and the dye test need nothing but a meter reading and food coloring. If you find a leak you can’t trace, a licensed plumber can find it with tools such as acoustic listening gear and cameras. First, know where your main shutoff is (Shut Off Your Home’s Water).

Check yourself

Tap an answer to check it, or open “Show the answer.”

A faucet drips once a second. About how much does EPA say that can waste in a year?
Show the answer
More than 3,000 gallons. More than 3,000 gallons a year.
How does EPA’s meter test work?
Show the answer
Read it, use no water for two hours, and read it again. Any change while no water is in use means a leak.
In EPA’s dye test, how long do you wait before checking the bowl?
Show the answer
10 minutes. Ten minutes, without flushing.
About how many gallons are in one CCF (100 cubic feet)?
Show the answer
748. 100 cubic feet × 7.48 gallons per cubic foot ≈ 748 gallons.

Go deeper

U.S. EPA WaterSense: Fix a Leak Week EPA WaterSense: Fix a Leak Week.
U.S. EPA WaterSense: Home Maintenance EPA’s home maintenance tips for saving water.
Being an Adult 101: Fix a Running Toilet Fix a running toilet.
Lesson 4: Fixtures and How They Work The animated toilet and its faults.

Sources

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A free course from Teddy Rook Book. It explains how plumbing works in general and follows U.S. sources; your local plumbing code, the authority having jurisdiction and manufacturers’ instructions are the final word.