Estimate a household's water use from everyday habits — showers, flushing, laundry, dishes and garden watering — in gallons per day, month and year.
Each habit is converted to gallons per day: showers are people times showers times minutes times flow rate, toilets are people times flushes times gallons per flush, and weekly loads of laundry, dishwashing and baths are spread across seven days using typical machine figures (35 gallons per laundry load, 6 per dishwasher load, 36 per bath). Older toilets use 3.5 to 5 gallons per flush and older shower heads 3 to 5 gallons per minute, so updating those two fields makes the biggest difference to an older home's total.
What is a typical household water use? Indoor use commonly lands around 50 to 70 gallons per person per day. A result far above that usually points to an old high-flow toilet or shower head, or a leak.
How can a leak be spotted from water use? If the estimate from habits is well below the metered bill, the gap is a leak suspect — a toilet that runs intermittently can waste hundreds of gallons a day without being obvious.