Contact US

PHONE (530) 346-2313
FAX (530) 346-6214

PO Box 702
Colfax, CA 95713

33 South Main St
Colfax, CA 95713

Sewer Collection System

The City of Colfax sewer collection facilities are managed by the Community Services Director. The City has several miles of storm drains, nine miles of sewer mains, four lift stations and a state of the art Aeromod Wastewater Treatment Plant. The City sewer rates are set via a complex process to ensure the facilities can be maintained in compliance with State regulations.

Utility Billing – Those served by the City of Colfax sewer system are billed bi-monthly based on the Equivalent Dwelling Unit (EDU) assigned to the property. Most homes are billed at 1 EDU; those with a second unit at 1.8 EDU’s; businesses are billed based on an evaluation in accordance with the City of Colfax Municipal Code Chapter 13.08. Because many homes do not have mail delivered directly to the home, please contact City Hall (530-346-2313) when property ownership changes.

Sewer bills are mailed to the property owner by the following schedule:

Billing Date Due Date Months of Service
January 1 February 28 January, February
March 1 April 30 March, April
May 1 June 30 May, June
July 1 August 30 July, August
September 1 October 31 September, October
November 1 December 31 November, December

Sewer bills may be paid

Sewer Rate Study – Adopted by Council 2024

NPDES Permit – The California State Water Board regulates Wastewater Treatment Plants in California. The current permit sets sampling and chemical testing requirements as well as discharge limitations.

Wastewater Treatment Plant Loan – The State Water Resources Control Board (SWRCB) holds the note for the treatment plant with a 1% rate of interest. Annual payments are $439,000 and the SWRCB requires the City keep a deposit of one year’s payment in reserve at all times.

Sewer System FAQ’s – The issues concerning the Colfax sewer system are complex for more detailed explanations, review Chapter 13.08 in the Colfax Municipal Code.

Wastewater Treatment Plant – The Wastewater Treatment Plant was built in 2008 The facility was designed to treat up to half a million gallons per day. To schedule a tour of the facility, contact the Chief Plant Operator (

More information regarding wastewater treatment plants is available at .

Sewer Lateral Program – The City owns and maintains the main lines to the Sewer Plant. Homeowners are responsible for the sewer line which runs from their house to the main line. In 2007 as part of a comprehensive plan to maximize efficiency and minimize sewer spills, the City Council adopted Ordinance 499 which formulated the Sewer Lateral Program. The ordinance requires a valid sewer lateral certificate is in place BEFORE a property can be sold. The homeowner must obtain a permit, retain a licensed California plumber for an inspection in the presence of City staff, and make any necessary repairs to ensure the lateral line is free of blockages or leaks. The certificate is generally good for 10 years.

Sewer Lateral Guidelines and Ordinance

Sewer Lateral Application

Inflow and Infiltration – Water from storm drains or leaks in the sewer mains can allow inflow and infiltration (I&I). I&I causes dilution in our sanitary sewer which decreases the efficiency of treatment and may cause the sewage volumes to exceed the design capacity of the Wastewater Treatment Plant. The City of Colfax is currently awaiting approval of a grant application which will allow study and projects to reduce I&I.

Sewer Collection System Map