Add your household fixtures and see an estimated daily and monthly water bill, including sewer charges and service fees.
Adjust your fixtures and click Calculate to see your estimated water bill
This free water bill calculator estimates your monthly water bill by adding up usage across common household fixtures — toilets, showers, faucets, washing machines, dishwashers, and outdoor irrigation — then applying your water rate, sewer rate, and any fixed monthly service fee, the same way most water utilities structure a bill.
Each fixture row multiplies gallons per use by uses per day to get a daily gallon figure, which the calculator sums across every fixture and multiplies by 30 for a monthly gallon estimate. That figure is divided by 1,000 and multiplied by your water rate for the water charge, and separately by your sewer rate for the sewer charge (many utilities bill sewer service based on metered water usage), then your fixed monthly service fee is added on top for a total estimated bill.
Homeowners and renters trying to understand what's driving their water bill, anyone considering water-saving fixture upgrades who wants to see the projected savings, and households comparing their actual bill against a usage-based estimate to spot a possible leak.
The exact formula this calculator uses
Summing usage fixture-by-fixture, rather than guessing a whole-household total, makes it easy to see exactly which habits or appliances drive the bill up or down.
Daily usage is multiplied by 30 to estimate a typical billing month; actual cycles range from 28-31 days depending on your utility's billing schedule.
Most utility bills combine a usage-based water charge, a usage-based (or capped) sewer charge, and a flat monthly service fee — this calculator models all three separately.
From reviewing default fixtures to reading your estimated bill
The calculator starts with common fixtures like toilets, showers, and faucets pre-filled with average usage.
Edit each fixture's gallons per use and how many times per day it's used to match your household.
Click "+ Add Fixture" for anything not listed, like an irrigation system, or remove rows that don't apply.
Enter your water rate and sewer rate per 1,000 gallons, plus any fixed monthly service fee, from a recent bill.
See your total monthly gallons and the estimated total monthly bill.
A typical household with and without outdoor irrigation
Using the default fixture list: toilet, shower, faucet, washing machine, and dishwasher, at a $5.00 water rate and $6.00 sewer rate per 1,000 gallons, with a $15.00 fixed fee.
Adding an outdoor irrigation fixture at 10 gal/use, 3 uses/day (≈30 minutes total).
Where an accurate water usage estimate saves money
See the dollar impact of shorter showers or a low-flow showerhead upgrade.
Compare an older high-flow toilet against a modern low-flow model's usage.
Estimate how much outdoor watering adds to a summer water bill.
Project monthly water costs when moving into a new home or apartment.
Compare an unusually high actual bill against this fixture-based estimate to help spot a possible leak.
Model different rate scenarios if you're evaluating a move to a different utility service area.
What this water bill calculator does well, and where it has boundaries
Get a more accurate water bill estimate
Summary: This water bill calculator estimates your monthly water bill from fixture-level usage, water and sewer rates, and a fixed service fee — free, instant, and entirely client-side. Pair it with the Electricity Bill Calculator for a complete household utility budget.
Common questions about estimating a water bill
Official guidance to complement this calculator
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