About 5 gallons of water are wasted every time teeth are brushed with the water running. If teeth are brushed twice per day, 3,650 gallons are wasted per year per person.
A family of four typically wastes enough water brushing teeth in a year to fill an above-ground pool. Leaving the water running while brushing teeth not only wastes water but wastes energy as well. Five minutes of running water uses as much energy as a 60-watt light bulb left on for 14 hours. Other ways to save water include filling the sink to wash dishes rather than let the water run, only running the dishwasher and washing machine when there's a full load, taking showers instead of baths, and watering plants with unused drinking water.