Water Usage Cost Calculator
Turn household water use — a daily total, a per-person figure or an activity-by-activity estimate — into a daily, monthly and yearly cost with water and sewer rates, fixed charges, tax and savings scenarios.
How it works
Daily use = your total, or people × per-person use, or the sum of showers (people × minutes × flow), toilets (people × flushes × water per flush), faucets, laundry and dishwasher loads ÷ 7, baths × 35 gal ÷ 7, outdoor ÷ 7 and leaks · Combined rate = water + sewer × sewer share (per 1,000 gal or per m³) · Monthly cost = (daily use × 30.44 ÷ 1,000 × combined rate + fixed charges) × (1 + tax) · Yearly = the same over 365 days
Water utilities meter usage in gallons, cubic feet (CCF) or cubic meters and charge per unit, and most also bill sewer on that same metered water, so the true price of a gallon is the two rates combined. Multiplying your daily use by the days in the period and the combined rate gives the usage part of the bill; fixed service charges and any tax come on top. Enter rates in whatever unit your bill uses — per 1,000 gallons, per CCF, per cubic meter or per gallon — and the calculator converts them. If you do not know your daily use, estimate it per person (the EPA’s US average is about 82 gallons a day at home) or activity by activity: showers from minutes and shower-head flow, toilets from flushes and gallons per flush, faucet use, laundry and dishwasher loads, baths, outdoor watering and typical leaks. The activity table shows what each use costs a month, and the savings table shows what cutting your use by 10–50% would save. Because sewer often costs more than the water itself, saving water indoors trims both charges at once; outdoor irrigation is sometimes exempt from sewer, which you can reflect with the sewer share.
Worked example
At 300 gallons a day and a combined $11 per 1,000 gallons ($5 water + $6 sewer), a month of 30.44 days uses about 9,132 gallons: $45.66 of water plus $54.79 of sewer, or $100.45 a month and $1,204.50 a year — 1.1 cents a gallon. Cutting use by 20% (to 240 gallons a day) would save about $241 a year.
Sources: EPA WaterSense — Statistics and facts · EPA WaterSense — How we use water
Frequently asked questions
Why is sewer charged on my water use?
Most homes have no separate meter for wastewater, so utilities assume water that comes in mostly goes down the drain and bill sewer on the same metered volume. Some bill sewer on your winter average or exempt a separate irrigation meter; set the sewer share under More options to match.
How do I find my rate?
Check a recent bill: divide the water usage charge by the units used (thousands of gallons, CCF or m³), and do the same for the sewer line. Enter the result in the unit your bill uses. If the bill uses tiered rates, divide the whole usage charge by the units to get your average rate, or use the water bill calculator for a tier-by-tier bill.
How much water does a person use a day?
The EPA estimates about 82 gallons (310 liters) per person per day at home in the US, rising well above that with lawn watering. Showers, toilets and faucets are the biggest indoor uses; a household with efficient fixtures can get below 50 gallons per person.
How much does a gallon of tap water cost?
Usually around a cent. At a combined $11 per 1,000 gallons, a gallon costs 1.1 cents and a liter about 0.3 cents — hundreds of times less than bottled water. The calculator shows your own figure.
What uses the most household water?
Toilets, showers, faucets and clothes washers dominate indoor use, with leaks a surprisingly large hidden share — around 9,400 gallons a year in the average US home. Use the By activity mode to see each one’s cost; low-flow fixtures and fixing a running toilet cut both the water and sewer portions of the bill.
Related calculators
This calculator is for educational purposes. Double-check important results before acting on them.