These calculators run entirely in your browser. Nothing you type is sent anywhere, stored, or logged. With JavaScript turned off the explanation below still works — the arithmetic is all shown.
Estimate a water and sewer bill
Water utilities bill in CCF (hundred cubic feet) or in thousands of gallons, and most charge sewer on top of water volume. One CCF is 748 gallons.
Estimated bill for this period
—
Fill the fields above to see your estimate.
CCF, HCF and thousands of gallons
Water is the one household utility that cannot be compared between two towns without a conversion, because there is no settled billing unit. Three are in common use:
- CCF — one hundred cubic feet, printed on some bills as HCF. One CCF is 748 gallons.
- Thousands of gallons, abbreviated kgal or shown as a rate per 1,000 gallons.
- Gallons, used by smaller systems whose meters register gallons directly.
A price per unit therefore means nothing until you know the unit, and utilities in the same state routinely choose differently. The same dollar figure buys a third more water priced per CCF than priced per thousand gallons, because 748 and 1,000 are not the same quantity.
The conversions are simple: gallons divided by 748 gives CCF, CCF times 0.748 gives thousands of gallons, CCF times 748 gives gallons. Enter the unit your bill uses, and check the total against a real bill before trusting any projection.
Sewer is billed on water, and often costs more
Nothing measures what leaves your house. Metering wastewater at every property would cost more than it recovered, so utilities charge sewer service on the volume of water that came in through the meter. Three consequences follow.
Every gallon is billed twice, once as water and once as sewer. Any estimate built on the water rate alone is half an answer.
The sewer rate is frequently the higher of the two. Collecting, conveying and treating wastewater to a discharge permit is more capital-intensive and more heavily regulated than distributing drinking water, and those costs land on the same volume. A sewer line larger than the water line is normal.
Water that never reaches the sewer is billed as sewer anyway. Irrigation, filling a pool, washing a car — all metered, all charged for treatment that never happens, unless the utility offers a way out. There are two: a separate irrigation or deduct meter, which you generally pay to install and which repays that cost only above a certain volume, and the winter-average cap below. The strategic point is simple: indoor savings cut both lines, outdoor savings cut one.
The winter-average sewer cap
Many utilities cap billable sewer volume at each customer's average consumption during a defined winter period, when outdoor irrigation is assumed to be zero and metered water is a fair proxy for what actually enters the sewer. For the rest of the year, sewer is billed on the lesser of actual usage or that average. On bills and tariffs it appears as winter average, winter quarter average, WQA, sewer cap or maximum billable sewer.
Finding out whether yours does this is the highest-value question you can ask about a water bill. Three ways to check:
- Compare the water volume and the sewer volume on a summer bill. If sewer is lower, a cap is in force and the bill is showing you its value.
- Read the utility's rate ordinance or tariff — the legal document, not the marketing page. Capping rules are written there, including which months form the averaging window.
Two details catch people out. The window is fixed, so anything unusual inside it echoes for a year: an undetected leak in February sets a high cap, and a long absence sets one so low that ordinary summer use sits above it.
If your utility caps, enter the cap here and the summer months stop looking absurd. If it does not, every gallon on the lawn really is billed twice, and that should shape how you irrigate.
Tiered rates, and what this tool does not model
Many utilities price in tiers: the first block of monthly consumption carries one rate, the next block a higher one. This is deliberate policy, usually called conservation or inclining block pricing. The essential first block — drinking, cooking, bathing, sanitation — stays affordable for every household, while the discretionary volume that drives peak summer demand carries the cost of the capacity built to serve it. Some systems vary tier widths by household size, and some add seasonal rates or drought surcharges.
That creates the distinction between an average rate and a marginal rate, and confusing the two is the commonest error in any bill estimate. Which to enter depends on the question:
- To reproduce a past bill, use your effective rate: the water commodity charge from a recent bill, excluding fixed charges and excluding sewer, divided by the units used.
- To model using more — a pool, a larger garden, another person in the house — use the highest tier rate you would reach, because the extra units are priced at the top and not at the average.
Stated plainly: this calculator models a flat per-unit rate for water and for sewer, an optional sewer cap, and fixed charges. It does not model tier breakpoints, seasonal rates or drought surcharges. The effective-rate method above is the honest workaround.
Fixed charges: the part usage cannot touch
A water bill is rarely all volume, and on a low-usage household the fixed part can be most of it.
- Base, service or customer charge — a flat amount per billing period covering mains, meter reading, billing and readiness to serve, usually charged separately for water and for sewer.
- Meter size charge — the base charge commonly scales with meter size. Homes with fire sprinklers or dedicated irrigation service carry larger meters and larger monthly charges for exactly the same water. An oversized meter can sometimes be downsized, permanently lowering the fixed charge.
- Stormwater fee — charged on impervious surface, roof and paving, rather than on water use, often as a flat rate or in equivalent residential units. It is the one line conservation cannot touch at all.
- Everything else bundled on — trash, street lighting, fire protection, capital-improvement surcharges, franchise fees and local taxes.
Work out the fixed share before estimating any saving, because it is the floor. If fixed charges are 40% of the bill, halving usage cuts the bill by 30%, not 50%. Where several households share one bill, the split bill calculator apportions fixed and variable parts separately.
Using the bill to catch a leak
The most valuable thing a water bill does is expose a leak, because leaks are silent, continuous and billed twice.
The diagnostic is a year-over-year comparison, not a month-over-month one. Usage is seasonal, so July against June tells you about the weather; July against last July tells you about the house. A step change that persists is a leak; a single spike that resolves was an event.
Confirmation happens at the meter, not on the bill. Shut off every fixture and appliance that uses water, then watch the low-flow indicator — the small triangle or dial that turns whenever water is moving. If there is no indicator, record the reading, wait an hour with everything off, and read again. The guide to reading a water meter covers the dial types and how to take a clean reading.
Suspects, ranked by volume wasted: a toilet flapper that has stopped sealing, by far the most common and almost silent; an irrigation valve that fails to close; a softener stuck in regeneration; and an underground supply line between meter and house, which shows as continuous flow with nothing audible indoors.
Once a leak is repaired, ask about a leak adjustment. Many utilities forgive part of the excess once, usually the sewer portion, but nearly all require a repair receipt and an application inside a short window, and none advertise it.
Frequently asked questions
How many gallons are in a CCF?
One CCF — one hundred cubic feet, sometimes printed as HCF — is 748 gallons. The figure comes from the volume of a cubic foot of water, roughly 7.48 gallons, multiplied by a hundred. That single conversion resolves most confusion on a water bill, because utilities that meter in cubic feet and utilities that bill per thousand gallons quote rates that look comparable and are not: a price per CCF covers 748 gallons, a price per thousand gallons covers 1,000. To convert your own usage, divide gallons by 748 to get CCF, or multiply CCF by 0.748 to get thousands of gallons.
Why is my sewer charge higher than my water charge?
Because sewer is billed on the same volume of water at a rate that is often higher. There is no meter on what leaves a house, so utilities charge wastewater service on metered water use as a proxy. Collecting, conveying and treating that water to a discharge permit is more capital-intensive and more heavily regulated than distributing drinking water, so the per-unit sewer rate frequently exceeds the water rate. It is normal, not an error. The practical consequence is that indoor savings cut two lines at once while outdoor savings cut only one — unless your utility caps sewer volume at a winter average.
How do I find out whether my utility caps sewer at a winter average?
Start with the bill itself. If the sewer volume shown for a summer month is lower than the water volume, a cap is being applied and the bill is telling you its value. If the two volumes always match, there probably is not one. Confirm in the utility's rate ordinance, tariff or rate schedule — the legal document, not the marketing page — which will state the months that make up the averaging window and when the average resets. Failing that, call and ask directly. The terms to listen for are winter average, winter quarter average, sewer cap and maximum billable sewer.
My water bill doubled with no change in habits. What should I check first?
Toilets, then irrigation, then the meter. A flapper that has stopped sealing runs continuously and silently, and it is the most common cause by a wide margin — put a few drops of food colouring in the tank, wait twenty minutes without flushing, and see whether colour reaches the bowl. Next, check irrigation for a valve that is not closing. Then shut off every water-using fixture and watch the meter's low-flow indicator: if it moves, water is still going somewhere, most likely a supply line between the meter and the house. Compare against the same month last year rather than last month, since usage is seasonal.