Loading Your sewer cap: what this winter sets for next year…
Your December, January and February water use becomes the cap your sewer bill is charged against from 1 July 2027. Work out what yours would be, and what one unit is actually worth.
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San Luis Obispo bills your sewer service against a cap: the most water you will be charged sewer on in any month. Your cap is your household’s average water use across December, January and February — measured over about fourteen weeks of winter, and applied to a whole billing year that begins four months after the measuring stops. The city states the rule on its rates page and nowhere else. This page shows where we are in that window, what your cap would be, and — the part that decides whether any of it matters to you — what the cap is actually worth.
Today, August 23, 2026
The winter measurement starts in 100 days.
Measured December 1, 2026 to March 10, 2027. Sets the cap billed from July 1, 2027 to June 30, 2028.
Between 1 December and 10 March the city measures how much water your household uses. The average of your December, January and February use becomes your sewer cap — the most water you will be billed for sewer in any month from 1 July 2027 to 30 June 2028.
Nothing you do after 10 March changes that number. Before then, two things move it: outdoor watering, which the city asks you to switch off for the window, and a leak, which quietly adds to every month it runs. Finding one now is worth more than finding it in April.
The city tracks three billing periods: your December usage, read in January; your January usage, read in February; and your February usage, read in March.
A single-family home: the published default, which applies until you have a winter’s history. New single-family customers are given a 5-unit cap until there is a winter of usage to average.
What the meter reads in a month when you are watering — May to October. This is the number that decides whether the cap saves you anything.
The rate for that year has not been set yet
Council has adopted sewer rates only through 30 June 2027. The rate that will actually apply from 1 July 2027 — the year this winter’s cap governs — has not been set. Every yearly figure on this page is worked out at today’s $11.14 a unit, so read it as this year’s money, not a quote for next year’s bill.
This is an estimate, not your bill
These figures come from the city’s published rates. They are not your bill. Your meter reading and your monthly statement are the real numbers, and your household’s own pattern of use will not match the simple year this page models.
Your monthly bill shows how many units of water you used, and your current sewer cap is printed on it too. One unit is one CCF — 748 gallons. Meters are read by hand each month, so a billing period is not exactly a calendar month.
One unit is 748 gallons. Because the cap averages December, January, and February, taking one unit off it means using one unit less in each of those months — 2,244 gallons across the whole window.
The city’s own advice for the measurement period: turn off irrigation and reduce outdoor water use during this time to help lower your sewer cap.
The city bills whole units and carries the remainder forward. Use 3.8 units in March and you are billed for 3, with 0.8 rolling into April; another 0.2 in April completes that unit. In the city’s own words, this “can create a scenario where a customer may use less water than the prior month and may receive a larger bill.”
| Month | Water used | Carried in | Billed | Rolls over |
|---|---|---|---|---|
| March | 3.8 | 0 | 3 | 0.8 |
| April | 0.2 | 0.8 | 1 | 0 |
The rollover is why a quiet month can carry a bigger bill than a busy one.
The sewer cap applies to residential properties only. Non-residential accounts have no cap at all — they are billed sewer on every unit of water they use.
Bills come monthly and are due on the 15th. Meters are read manually each month.
Sewer usage is not tiered. Every unit up to your cap is charged at the same rate, and nothing above the cap is charged at all. Water is tiered; sewer is not.
| From | Rate | Per unit, up to the cap | Monthly service charge |
|---|---|---|---|
| July 1, 2024 | 2024–25 | $9.82 | $24.52 |
| July 1, 2025 | 2025–26 | $10.46 | $26.11 |
| July 1, 2026 | 2026–27 — in force now | $11.14 | $27.81 |
Council adopted this schedule on 17 June 2025. Each row takes effect on 1 July of its year.
A 5% Utility Users Tax applies to the whole water portion of your bill — the monthly base fee and every water charge. The city does not state it for sewer, so it is not applied to any of the sewer figures on this page.
The Customer Assistance Program takes 20% off each monthly water and sewer bill. (The city’s rates page still says 15%; the program page says 20%.)
You also qualify if your household income is below twice the federal poverty rate. The 2026 ceilings are:
| People in the home | Yearly income under |
|---|---|
| 1 person | $31,920 |
| 2 people | $43,280 |
| 3 people | $54,640 |
| 4 people | $66,000 |
| 5 people | $77,360 |
| 6 people | $88,720 |
| 7 people | $100,080 |
| 8 people | $111,440 |
Add $11,360 for each additional person.
The discount has to be renewed every November.
It is not backdated. The discount runs from when you apply, so applying earlier is worth more than applying later.
The measurement window can move
Under Resolution No. 10587 the Utilities Director may change the months that are averaged: if two consecutive measurement months receive 10% or less of normal rainfall, if a drought emergency is declared and rainfall is 40% or less of normal, or for another unforeseen regional condition. If that happens, the city’s rates page is where it will be announced.
The cap is the maximum amount of water use that will be billed for sewer service. It is there so you are not charged sewer rates on water that goes onto the garden and never reaches the sewer. Water and Sewer Rates.
From 1 July 2026 single-family water is $9.51 a unit for the first 5 units, $10.95 for units 6–12 and $18.88 above that, on top of a $33.67 monthly base fee — and the 5% Utility Users Tax applies to all of it. This page works out the sewer side only.
Utility Billing, City of San Luis Obispo
Starts in 100 days
Winter water use from December 1, 2026 sets the most you are billed for sewer next year.