Water and Sewer Bills: Gallons, CCF and the Winter Average
Why this matters
On many water bills, the sewer charge is larger than the water charge, and the house has no sewer meter. The utility infers sewage from metered water, and some utilities do it once a year from a winter period, then bill that figure for the next twelve months. That single rule is why a toilet that ran unnoticed for six weeks in February can raise a household's sewer charges every month until the following winter. A plumber who fixes the flapper and says "you're all set" has fixed the water half and left the customer to discover the sewer half on every bill after. Knowing how the bill is built is what lets you tell them about it.
Units on a water bill
- CCF is 100 cubic feet. One cubic foot of water is about 7.48 gallons, so one CCF is 748 gallons. Some utilities call this one "unit" or one HCF (hundred cubic feet).
- Kgal or TG is 1,000 gallons. One kgal is 1,000 divided by 748, or about 1.34 CCF.
- Gallons directly, on meters and bills that register in gallons.
The meter face tells you which unit it registers, and it may not match the bill: a meter can read in cubic feet while the bill is in CCF, so the last two digits of the meter are dropped on the bill. Read the unit printed on the meter register, not the one you expect (see related: Reading Water Meter + Leak Detection Reference).
The bill, laid out
SERVICE 01/05 TO 03/06 BILLING DAYS: 60
METER SIZE 5/8 IN READ CODE: A
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METER PREV CURR UNITS USED
W-30881 2,184 2,221 CCF 37 [1]
37 CCF x 748 = 27,676 GALLONS
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WATER
Base charge (by meter size) fixed [2]
Usage 37 CCF in tiers at W1, W2 [3]
SEWER
Base charge fixed [2]
Usage 37 CCF x S (billed sewer volume) [4]
OTHER
Stormwater fee fixed [5]
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NOTE: BILLS IN THIS PERIOD SET YOUR SEWER
VOLUME FOR APR THROUGH MAR (WINTER AVERAGE) [4]
[1] Reads and volume. 2,221 minus 2,184 is 37 CCF. Times 748 is 27,676 gallons. Over 60 days that is 461 gallons a day. Water bills are often bi-monthly or quarterly, so always divide by days before comparing; a 60-day bill and a 90-day bill are not comparable on totals.
[2] Base charges. Fixed per period, usually set by meter size, for both water and sewer. A larger meter carries a larger base charge whether or not the house uses more water.
[3] Water usage. Charged per CCF or per kgal, often in rising tiers, so the last units cost more than the first. Tiers for water work the same way they do for electricity (see related: Tiered and Seasonal Rates: Why the Last Kilowatt-Hour Costs More).
[4] Sewer usage, and how the billed volume is set. This line is charged on a billed sewer volume, which may not be the same as the water you just read. Utilities set it in several ways, and the tariff says which:
- Actual metered water each period. Sewer volume equals water used on every bill, sometimes reduced by a fixed percentage for water that never reaches the drain.
- A winter average. Sewer volume is set from use in a winter period, when little water goes on lawns, and applied to the following year's bills. This is what the note on the mock bill says.
- The lesser of actual and the winter average. Each bill is charged sewer on whichever is smaller, so summer irrigation is excluded but a drop in use is still rewarded.
- A separate irrigation or deduct meter. Water through a second meter is billed for water only, never sewer.
Practice varies by utility, not by state, and one city can differ from the next. Read the customer's own tariff or call the utility before telling them how their sewer volume works.
[5] Fixed fees. Stormwater, fire protection and similar charges, flat per period or per property. They do not move with use.
Worked example: a February toilet leak under a winter average
The household's winter bills normally show about 20 CCF per 60-day period. This bill shows 37. The utility uses the winter-average method, and this bill falls in the averaging period.
Size the leak. 37 minus 20 is 17 CCF extra. 17 times 748 is 12,716 gallons over 60 days, or 212 gallons a day. That is about 8.8 gallons an hour (212 divided by 24), or roughly 0.15 gallons a minute. A flapper that never fully seats, or a fill valve that never quite shuts off, can run at that rate silently, and it is in the range a meter leak check finds easily (see related: The Water Bill From a Toilet Nobody Heard Running).
Check the per-day figures. Normal use: 20 CCF is 14,960 gallons, over 60 days 249 gallons a day. With the leak: 461 gallons a day. 461 minus 249 is 212. The two routes agree.
The water side. The leak cost 17 CCF of water usage once, on this bill, plus whatever share of it fell into a higher tier.
The sewer side, under a winter average. If this bill sets the billed sewer volume at 37 CCF per period for the next year of bi-monthly bills, that is 6 bills at 37, or 222 CCF of sewer volume. Without the leak it would have been 6 at 20, or 120 CCF. 222 minus 120 is 102 CCF of extra sewer volume, which is 17 CCF times 6 bills. The leak is charged on the water side once and on the sewer side six times.
The same leak under actual metered sewer. The sewer charge on this bill rises by 17 CCF, and the next bill, after the repair, goes back to normal. The extra sewer volume is 17 CCF, a sixth of the winter-average case.
Under the lesser-of method. Once the leak is fixed, each bill is charged on actual use whenever that is below 37 CCF, which in winter it will be. In summer, when irrigation pushes actual use up, the cap is now 37 instead of 20, so the summer sewer charges are higher than they would have been. The cost lands in the irrigation months rather than evenly across the year.
The question to ask the utility. Many utilities have a leak adjustment or a sewer re-averaging policy, typically requiring proof of the repair: a plumber's invoice, a dated photo of the replaced part, a follow-up meter read showing normal use. Policies differ in what they cover, how far back, and whether they adjust water, sewer or both. Do not promise the customer an adjustment; tell them the policy may exist and what evidence the shop can give them.
What the plumber says at the door. "The toilet was running about 200 gallons a day. Your utility sets your sewer charge from winter bills, and this one was in that window, so call them about a leak adjustment and keep this invoice. If they don't adjust it, the higher sewer charge may stay on your bills until next winter." That sentence is the difference between the customer blaming the shop in July and thanking it in March.
Reading the winter period on the bill
The winter-average rule only matters if the leak lands in the averaging window. Utilities define it by billing dates, not calendar months: a "December through February" window may in fact be the bills whose read dates fall in that span, which can include days in November or March. The bill or the utility's website names the window. Check it before you tell a customer their summer leak has a year-long tail, because under a winter average it usually does not.
The rule cuts both ways. A household that is away for six weeks in January can lock in an unusually low sewer volume for the year. That is the utility's rule, not a trick, and the shop has no part in it.
What changes the reading
A pool fill or a new irrigation system on the house meter. Under actual-metered sewer, water poured into a pool is charged as sewage. Some utilities let customers request a pool-fill credit or install a deduct meter. Under a winter average, a spring pool fill costs water only.
Estimated reads. A water meter that was not read during the averaging period can set the year's sewer volume on an estimate. If the next actual read reveals the estimate was high or low, ask the utility whether the average is recalculated (see related: Estimated Versus Actual Meter Reads and the Catch-Up Bill).
Shared meters. Some duplexes and older multi-unit buildings share a meter, and the bill carries every unit's use.
Private well and septic. Neither bill exists. A leak on a well system shows up as pump run time on the electric bill instead (see related: The Well Pump That Ran Up the Electric Bill).
Where readers go wrong
Comparing bills of different lengths. A 90-day bill is half again as long as a 60-day bill. Divide by days first (see related: How to Compare Two Bills With Different Billing Days).
Confusing CCF with cubic feet. A meter that reads in cubic feet looks like it shows a hundred times the CCF on the bill. It does: two more digits.
Telling the customer the leak is "all fixed." The water is. Under a winter average, the sewer billing is not, until the utility says so or the next averaging period resets it.
Assuming every utility averages. Many bill sewer on actual metered water every period. Saying "your sewer is set for the year" to a customer whose utility does not do that is wrong in the other direction, and it sends them on a phone call that goes nowhere.
How to verify you read it right
- Current minus previous read equals the usage printed, in the unit on the meter register.
- Gallons are CCF times 748, and per-day use is gallons divided by billing days.
- You know which of the sewer methods the customer's utility uses, from the tariff or the utility, not from the last utility you dealt with.
- If a leak landed in an averaging period, the customer has been told what that may mean for the year and what proof to keep.
References
- See related: Reading Water Meter + Leak Detection Reference
- See related: How to Walk a Customer Through a Water Meter Leak Check by Phone
- See related: The Water Bill From a Toilet Nobody Heard Running
- The local water and sewer utility's rate ordinance or tariff, which sets the sewer billing method, averaging window and leak adjustment policy for that service area