OWTS Technical Manual

The purpose of this manual is to provide guidance to owners, designers, and installers of onsite wastewater treatment systems. It is not authoritative or complete, and is subject to updates and revisions. 

Onsite Wastewater Treatment System Technical Manual - last revised 2015


2019 Ventura County Building Code Revisions 

The 2019 Ventura County Building Code will be effective beginning January 1, 2020. Revisions pertaining to OWTS include editorial and formatting changes, as well as substantive amendments which will affect the plan review, design, and installation of OWTS in unincorporated Ventura County. Please review the following documents for more information or contact one of the Liquid Waste Program staff specialists:


New OWTS Standards (Ventura County Local Agency Management Program)

In June 2012, new standards pertaining to OWTS were adopted by the State Water Resources Control Board and become effective in 2013. The Ventura County Board of Supervisors directed the Environmental Health Division to review current policies and regulations, and prepare proposed changes to the existing local OWTS regulatory program to implement the new State standards.

The Ventura County Local Agency Management Program, or LAMP, was approved by the Board on August 7, 2018. Please click on the following link to review the LAMP

Please click on the following links for more information the State OWTS Policy:


Areas of Special Concern in Ventura County

Ventura River Watershed Total Maximum Daily Load Special Study

Areas of the Ventura River Watershed have been placed on the Clean Water Act, Section 303(d) list of impaired water bodies, including parts the City of Ojai, the City of Ventura, and unincorporated Ventura County. Resolution No. R12-011 was added to the Los Angeles Region Water Quality Control Basin Plan in 2013, and incorporates the Total Maximum Daily Load for Algae, Eutrophic Conditions, and Nutrients in the Ventura River and its Tributaries (Algae TMDL). The Environmental Health Division conducted a "Special Study" designed to investigate the influence of Onsite Wastewater Treatment Systems (OWTS) on surface water quality and identify OWTS areas that are contributing substantive nutrient loads to the Ventura River and its tributaries as assigned by the Algae TMDL. Please click on the links below for more information on the Algae TMDL and the Special Study:

 Additional Guidance & FAQ's

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