Household Water Use Calculator
See where your indoor water actually goes — showers, toilets, faucets, laundry, and the dishwasher — broken down by day, month, and year, using fixture rates you can tune to match your own home.
Estimated water use
How the estimate works
Each category is a simple multiplication: how many times a fixture is used per day (or per week for laundry and dishes), how long or how many times, and the fixture's flow or per-use volume. Showers multiply people × showers per day × minutes × flow rate; toilets multiply people × flushes per day × gallons per flush; and so on for faucets, laundry, and the dishwasher.
Adding every category together gives a daily total, which is then scaled to a month (×30) and a year (×365) and divided by household size for a per-person figure — useful for comparing against published national averages, which are almost always quoted per person.
Frequently Asked Questions
Where do the default fixture numbers come from?
They're commonly cited WaterSense and Energy Star reference figures: a 2.1 gallon-per-minute showerhead, a 1.6-gallon low-flow toilet flush (the US federal standard), a 1.5 gpm faucet, a 25-gallon efficient washing-machine load, and a 6-gallon efficient dishwasher load. Every one of them is editable — swap in your own fixture's rated flow if you know it for a more accurate estimate.
Why does laundry show a fractional 'gallons per day' figure?
Laundry and dishwasher loads are usually counted per week, not per day, so the calculator spreads a weekly total evenly across seven days to combine it with the daily shower, toilet, and faucet figures. Four loads a week at 25 gallons each averages out to about 14.3 gallons a day.
How can I use this to find where to cut back?
Run the calculator once with your current fixtures, then again with a lower-flow showerhead or toilet swapped in, and compare the totals. The category breakdown (showers, toilets, faucets, laundry, dishwasher) shows which use is actually the largest in your house, which is usually where a fixture upgrade pays off fastest.
Why doesn't this match my water bill exactly?
This estimates indoor fixture use only — it doesn't include outdoor irrigation, pool refills, or unusual habits like long baths, and it assumes the default or entered rates match your actual fixtures. Treat it as a planning estimate, and use the water-savings calculator once you have an actual metered baseline to compare against.
Planning estimate only, based on typical fixture rates and the values you enter — not a metered reading. Compare against an actual water bill for your real baseline usage.