Water Bill Calculator
Estimated water cost from daily usage and your rate.
Input sheet
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Water utilities usually bill per thousand gallons, which makes it hard to picture what a long shower or a leaky toilet really costs. This calculator estimates the usage portion of your bill from daily gallons and your rate.
How it works
Daily gallons times billing days gives total usage; divided by 1000 and times your rate gives the usage charge.
Daily gallons multiplied by the number of billing days gives total usage; dividing by 1,000 and multiplying by your rate per thousand gallons gives the usage charge. It also shows a per-day cost and a standardized 30-day figure for comparison.
This covers water usage only. Real bills typically add a separate sewer charge (often tied to your water use) and fixed monthly service fees, so your actual statement will run higher than the usage estimate.
Usage charge = (gallons per day × billing days ÷ 1000) × rate per 1000 gallons.
Worked examples
300 gallons per day over a 30-day cycle at $5 per 1000 gallons. → $45.00 in usage (9,000 gallons), about $1.50 per day.
300 × 30 = 9000 gal; 9000 ÷ 1000 × 5 = 45.
A family using 500 gallons per day over 31 days at $6 per 1000 gallons. → $93.00 in usage (15,500 gallons).
500 × 31 = 15,500 gal; 15.5 × 6 = 93.
Tips & gotchas
- Find your rate and any tiered pricing on your bill — many utilities charge a higher rate above a usage threshold, which this flat estimate does not capture.
- Average indoor use is roughly 50–80 gallons per person per day; outdoor irrigation can dwarf that in summer.
- A running toilet can waste hundreds of gallons a day — if your estimate looks low versus your actual bill, check for leaks.
- Remember the sewer charge: many utilities bill sewer as a multiple of your water use, so cutting water often cuts sewer too.
FAQ
Why is my actual bill higher than this estimate?
Real statements add sewer charges, fixed service or meter fees, stormwater fees, and taxes. This figure is the water-usage portion only.
How do I know my gallons per day?
Divide the gallons (or read the usage) on a recent bill by the number of billing days, or read your meter at the start and end of a day.
What is a CCF or HCF on my bill?
Some utilities bill in hundred-cubic-feet units. One CCF equals about 748 gallons — convert your rate to per-1000-gallons before using this tool, or your estimate will be off.
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