Water use is easy to underestimate because most of it disappears down the drain a few gallons at a time. This calculator adds up a typical day in your home, from showers and toilets to laundry and lawn watering, shows which uses dominate, and estimates what WaterSense-labeled fixtures would save.
How to use the water usage calculator
- Enter the number of people in the household.
- Fill in bathroom habits: showers per person, minutes per shower and showerhead flow, baths per week, toilet flushes and gallons per flush.
- Fill in kitchen and laundry use: faucet minutes, dishwasher loads and laundry loads per week, with gallons per load.
- Add outdoor watering minutes per week and any leaks you know of.
- Optionally enter your water and sewer price per 1,000 gallons to see costs.
Defaults reflect common US fixtures and habits, so adjust anything you know is different.
Water usage formulas
The total converts to liters at 3.785 liters per gallon. The WaterSense comparison caps showerheads at 2.0 gpm, toilets at 1.28 gallons per flush and faucets at 1.5 gpm.
Worked example
A family of four with the default habits: one 8-minute shower each at 2.5 gpm, 5 flushes each at 1.6 gallons, 8 faucet minutes each at 2.2 gpm, one bath a week, four dishwasher loads and six laundry loads:
Showers: 4 × 8 × 2.5 = 80 gal · Toilets: 4 × 5 × 1.6 = 32 gal · Faucets: 4 × 8 × 2.2 = 70.4 gal
Bath 35 ÷ 7 = 5 gal · Dishwasher 16 ÷ 7 = 2.3 gal · Laundry 120 ÷ 7 = 17.1 gal
Total: about 207 gallons a day (783 liters), 52 gallons per person, roughly 6,300 gallons a month.
With WaterSense showerheads, toilets and faucets, the same habits would use about 45 gallons a day less.
Typical flow rates
| Fixture | Older or standard | Current federal maximum | WaterSense |
|---|---|---|---|
| Showerhead | 3–5 gpm or more (older) | 2.5 gpm | 2.0 gpm or less |
| Toilet | 3.5–7 gal per flush | 1.6 gal per flush | 1.28 gal or less |
| Bathroom faucet | 3+ gpm | 2.2 gpm | 1.5 gpm or less |
| Clothes washer | 30–40 gal per load | — | ENERGY STAR about 14 gal |
| Dishwasher | 6–10 gal per load | — | ENERGY STAR about 3–4 gal |
| Garden hose | 5–20 gpm | — | — |
Where to save water
Fix leaks first
A faucet dripping once a second wastes more than 3,000 gallons a year (about 8 gallons a day), and a toilet flapper that leaks silently can waste far more. To test a toilet, put a few drops of food coloring in the tank and wait 15 minutes without flushing; color in the bowl means a leak.
Upgrade the big users
In most homes, toilets and showers use the most water. Swapping a 3.5-gallon toilet for a 1.28-gallon model saves over 11 gallons a day per person at five flushes. A WaterSense showerhead saves water and the energy to heat it, which also lowers your power or gas bill.
Water outdoors wisely
Outdoor watering can double summer use. Water early in the morning, check sprinklers for overspray onto pavement, and adjust the schedule to rainfall.
To estimate the energy side of hot water, use the electricity cost calculator. The gallons to liters converter converts results, and the tank volume calculator sizes rain barrels and storage tanks.
Frequently asked questions
How much water does the average household use?
The EPA estimates that the average American family uses more than 300 gallons of water a day at home, with roughly 70% used indoors. Indoor use alone is often 50 to 80 gallons per person a day.
How much water does a shower use?
Multiply minutes by the showerhead flow rate. Federal rules cap new showerheads at 2.5 gallons per minute, so an 8-minute shower uses up to 20 gallons. A WaterSense showerhead (2.0 gpm or less) cuts that to 16 gallons.
How much water does a toilet use per flush?
Toilets sold in the US since 1994 use no more than 1.6 gallons per flush, and WaterSense models use 1.28 or less. Older toilets can use 3.5 to 7 gallons, which makes the toilet the biggest indoor water user in many older homes.
How much water do leaks waste?
The EPA estimates household leaks can waste nearly 10,000 gallons a year, about 27 gallons a day. A running toilet alone can waste 200 gallons or more a day, so leaks are worth fixing quickly.
How do I read my water bill units?
Many utilities bill in CCF (hundred cubic feet). One CCF is 748 gallons. Others bill per 1,000 gallons. The calculator shows monthly use in CCF when no price is entered.