Sewer Service Rates

Concord owns, operates, and maintains the wastewater collection system. Operation of the wastewater collection system consists of: Cleaning and televising the underground lines, making repairs and long-term capital projects, customer service calls and assessing the annual property levies. City of Concord also operates and maintains the wastewater collection system for the City of Clayton.

The majority of the Sewer Fund’s expenses are attributed to the daily treatment of Concord’s sewage at the Central Contra Costa Sanitary District’s (Central San) treatment plant. The costs include the maintenance, operation, and capital improvements at the treatment plant; and a proportional share (based upon population), of the cost to operate the Household Hazardous Waste Facility (HHWF). Together these items make up approximately 75% of the fund’s annual expenditures. The remaining expenses include the cost of operating the city’s sanitary sewer system, routine maintenance, replacement and repair, and emergency reserves.

The following are links to sewer service charge information and notifications:

City of Concord Prop 218 Mailer

City of Clayton Prop 218 Mailer

City of Concord Sewer Rate Study -- May 2023

Sanitary Sewer master plan

City of Concord Sanitary Sewer Master Plan

Process for Calculating Commercial Sewer Levy 

1) Obtain winter water usage from Contra Costa Water District (CCWD) – The data from CCWD contains total water used for each commercial meter and total number of days between those readings. Water use is measured in units. Each unit equals 748 gallons.

2) Divide total winter water usage by the total number of days between readings to obtain an average daily winter water usage in units of water.

3) Multiply the average daily winter water usage by 365 to obtain an annual usage in units of water.

4) Multiply the annual water usage units by the commercial amount (this amount is determined based upon the type of business, the list of charges are published in the Concord Municipal Code).

5) There is a minimum charge for each business – typically this is the same amount as the residential per unit charge and is listed each year in the City of Concord Master Fee Schedule.


CCWD Water Usage for business X – 600 units of water over 182 days

600/182 = 3.296 Units/Day

3.296 X 365 = 1,203 Total Units of Water

1,203 Units X $4.52/Unit = $5,437.56

Sewer SERVICE Rates Q&A

Q: How is the Sewer Service charge collected? 

A: The Sewer Service Charge is collected annually via your property taxes. It appears in the “Special Taxes & Assessments” portion of the bill as either: Concord Res Sewer, Clayton Res Sewer, Concord Com Sewer, or Clayton Com Sewer.

Q: Why has my bill increased dramatically from last year?

A: Your sewer service rate assessment is based on water usage. If your assessment has increased dramatically it means you used more water. 

Q: Are there any discounts for low incrome or seniors? 

A: No, there are no discounts based on income, age, or any other factor. 

Q: Why do I have to pay so much? 

A: The City of Concord Sewer Rates are in line with other Bay Area cities.