HCF Cost Calculator

What an HCF is on a water bill

HCF stands for hundred cubic feet, and CCF printed on a bill means the same thing: 100 cubic feet of water. Utilities like the unit because residential meters count in cubic feet, so the meter has to roll through exactly 100 cubic feet before the bill moves by one unit. One HCF holds 748 gallons, or 2.83 cubic meters. The gallon figure traces back to the USGS Water Science Glossary, which lists an acre-foot as 43,560 cubic feet and 325,851 gallons. Divide 325,851 by 43,560 and you get 7.48 gallons in a single cubic foot, so 100 cubic feet holds 748 gallons.

Seattle Public Utilities, which bills in CCF, puts it the way most utilities would: one CCF equals 100 cubic feet or 748 gallons of water. Some utilities round to 750, and a few bill in thousands of gallons or in cubic meters instead, so it pays to read the unit line on the bill before comparing rates with anyone in another state.

To picture the size, one HCF would fill a 50 gallon bathtub about 15 times. A family that uses 300 gallons a day, the figure EPA's WaterSense program uses for a typical American household, burns through one HCF every two and a half days.

Converting HCF to gallons, cubic meters and liters

The conversion is one multiplication. Gallons equals HCF times 748. Cubic meters equals HCF times 2.83168, because one cubic foot is 0.0283168 cubic meters and an HCF carries 100 of them. Liters are the cubic meter figure times 1,000. Going the other way, divide gallons by 748 to get HCF, which is the move you need when your meter reads in gallons but the rate card quotes a price per HCF.

The 12 HCF row matters for the worked bill below: 12 HCF is 8,976 gallons, which is what a three person household with summer irrigation might use across a 60 day billing period. Type any figure from your own bill into the calculator above and switch the unit selector if your utility prints gallons or cubic meters rather than HCF.

Larger accounts sometimes quote acre-feet instead. One acre-foot is 43,560 cubic feet, which is 435.6 HCF or 325,851 gallons, so a 100 acre-foot irrigation contract is 43,560 HCF. The unit shows up in farm, ranch and golf course water rights far more often than on a house bill, but the conversion runs through the same 7.48 gallons per cubic foot.

How tiered HCF rates work

Many utilities price water in an inclining block: the first block of HCF in a billing period is cheap, and each block above it costs more. The price on the tier applies to the HCF inside that block only, not to the whole bill, which is why the average price per HCF and the marginal price per HCF are different numbers.

Seattle's 2026 residential rate card is a clean example. Peak season runs from May 16 through September 15, and the tier lines reset with each 60 day bill:

Off peak, from September 16 to May 15, the same utility charges a single $5.82 per CCF with no tiers. On top of the volume price sits a base service charge, $21.35 a month for the standard 3/4 inch meter in 2026, which lands on the bill whether you use one HCF or fifty. The calculator above starts with these Seattle numbers so you can see the mechanics, then you swap in your own utility's tier widths and prices from its rate card.

A worked bill: 12 HCF over 60 days

Take a three person household that used 12 HCF between two summer readings. Twelve HCF is 8,976 gallons. The first 10 HCF bill at the tier 1 price: 10 times $5.98 is $59.80. The remaining 2 HCF fall in tier 2: 2 times $7.39 is $14.78. The water charge is $74.58.

Sewer in Seattle is billed per CCF of water used, at $20.18 per CCF in 2026: 12 times $20.18 is $242.16. The base charge adds $21.35 for each of the two months, another $42.70. The bill totals $74.58 plus $242.16 plus $42.70, which is $359.44. Spread across the 8,976 gallons delivered, that is $40.04 per 1,000 gallons and $29.95 per HCF, or $1.97 per person per day.

Notice what the water price did and did not do. Water itself was about 21 percent of the bill. Cutting use by 10 percent, to 10.8 HCF, drops the total to $326.36, saving $33.08 on this bill and about $198.50 over a year of similar periods. That saving comes from both sides of the meter: less water purchased, and 1.2 fewer HCF of sewer billed at $20.18 each.

What happens when use crosses the top tier

The same household that waters the lawn heavily might hit 30 HCF in a 60 day period. Tier 1 still caps at $59.80. Tier 2 now carries 20 HCF: 20 times $7.39 is $147.80, so the water charge is $207.60. Sewer is 30 times $20.18, or $605.40, and fixed charges stay at $42.70. The bill reaches $855.70, an average of $28.52 per HCF.

At 40 HCF the account crosses into tier 3. Tier 2 fills at 26 HCF for $192.14, and the 4 HCF above the 36 line bill at $11.80 each, another $47.20. Water comes to $299.14, sewer to $807.20, and the bill lands at $1,149.04, or $28.73 per HCF on average.

Two things are worth taking from those runs. First, the average price barely moves even though the marginal price does: every HCF above 36 costs $11.80 of water plus $20.18 of sewer, a combined $31.98, while HCF 1 through 10 cost $26.16. Second, volume tames the average because the $42.70 of fixed charges gets spread across more units. The calculator shows both the average per HCF and the tier by tier breakdown, so you can see which HCF pushed the bill up.

Fixed charges, sewer and your real price per HCF

A price per HCF quoted from a rate card is only the water half. Utilities add a fixed base charge, and most bill sewer on the same HCF that ran through the meter, sometimes all year and sometimes based on winter usage. EPA's WaterSense program, working from the American Water Works Association rate survey, estimated 2024 national average rates of $7.74 per 1,000 gallons for water and $9.09 for wastewater.

Convert those to billing units and the averages look like this:

At the combined national average, the 12 HCF example bill would cost 8.976 thousand gallons times $16.83, about $151, against $359.44 in the Seattle case. The gap is mostly sewer pricing and the base charge, not water. EPA's own water bill explainer shows the same pattern on a sample bill, where fixed charges and sewer can rival the water line even at modest use.

Commercial accounts add a wrinkle a house bill never shows. A restaurant or a laundry usually pays a commodity charge per HCF plus a demand component tied to meter size, and some utilities add a strength surcharge on wastewater that arrives dirtier than household sewage. Those lines explain why two buildings on the same street can pay different prices for the same 20 HCF, and why the published rate card, not the bill total, is the document to compare.

How to check your own bill for mistakes

You can rebuild any bill from its raw materials. Read your meter, which for most homes counts in cubic feet, and subtract the previous reading. Divide by 100 to get HCF, multiply by 748 for gallons, then apply your utility's tiers, its sewer rate and its base charge. If the rebuilt total is more than a dollar or two off the bill, something in the bill deserves a second look: a misread meter, a tier applied over the wrong billing days, or sewer billed on summer irrigation rather than winter usage.

A jump in HCF with no change in habits usually means a leak. EPA's Fix a Leak Week guidance estimates household leaks waste close to 10,000 gallons per home per year on average, and a running toilet alone can waste about 200 gallons a day, which is a quarter of an HCF every day. The test costs nothing: shut off every fixture, then watch the meter. Any movement with everything off points to a leak between the meter and the drain.

Keep one caution in mind as you use the tool. Rate cards change, sometimes mid year, and the figures stored in this page's defaults are Seattle's published 2026 residential rates and EPA's 2024 national estimates. Enter your own utility's numbers for anything that matters, and treat the output as an estimate to check against the bill, not a quote from the water company.

Reading the dial takes a minute. Most meters print a six digit odometer in cubic feet plus a sweep hand for the last cubic foot, and the utility bills whole hundreds, so the last two digits never reach the statement. Write the reading down when each bill arrives; after three or four statements you have your own usage history, which is the fastest way to spot a spike that weather does not explain.

A landscape meter deserves its own check. Many utilities bill a dedicated irrigation meter without the sewer line, since that water never reaches the wastewater plant, so the effective price per HCF on it is lower than on the house meter. Ask whether a second meter is allowed and what its base charge would be before you price a sprinkler upgrade.