it’s always important to be mindful of water waste, but it’s easy for water loss to go unnoticed. even brushing one’s teeth sends gallons of water down the drain at a rate of 1 gallon per minute, or 2 gallons per minute from an older faucet. brushing three times per day would waste 3 to 6 gallons per day for just one person if they only brushed their teeth for 1 minute.

think about that on a larger scale. for a household of four people, that’s 12 gallons per day — if everyone was using a water-efficient faucet. that might not seem like a lot, but it adds up. a neighborhood with 25 of those households — 100 people — would use 300 gallons in a single day. if those hypothetical households have old plumbing? now the residents are wasting 600 gallons of water in a day for no reason. that’s the equivalent of filling more than 16.5 standard-sized bathtubs a day.

the easiest solution is to simply turn off the water while you brush. that is, only turn the water on to wet your toothbrush and later to rinse it off when you’re done brushing.

of course, it’s possible to save even more water. residents of east porterville, calif., have had to turn to alternative daily habits in the wake of dried up personal wells. many of them rely on delivered bottled water to complete small tasks like tooth brushing because turning off the faucet is no longer an option: it’s already off.

take a cue from east porterville. next time you brush your teeth, instead of running the water, fill a cup or bottle and brush your teeth with only the water in that container. you’d cut your water use to approximately 4.5 cups per day on average — instead of 4.5 gallons — a 94% decrease. that’s a huge difference.

imagine that hypothetical neighborhood again. making the switch to a cup or bottle would save more than 200,000 gallons a year, which is enough to fill more than 8 average swimming pools (at 24,300 gallons each). and that’s for just 100 people. the u.s. population is hovering close to 322 million. on that scale, if everyone made this small change, the u.s. could save 1.4 billion gallons — nearly 56,000 home swimming pools’ worth! — of water from just going down the drain every day.