Onsite Wastewater Treatment System Frequently Asked Questions
What is an Onsite Wastewater Treatment System?
An Onsite Wastewater Treatment Systems (OWTS) is a privately owned and maintained sewage disposal system. They are commonly referred to as septic systems. All OWTS have two basic components: a two-compartment septic tank and a disposal field. The septic tank serves to separate and store solid material and the disposal field allows wastewater to percolate into the ground. In Ventura County, there are two general types of OWTS: conventional and alternative. Conventional systems use leach lines, leach beds, or seepage pits for the disposal field component. Alternative systems use an above-ground mound or below-ground gravity sand filter for the disposal field component.
Who is qualified to design my own?
Due to the potential adverse impacts to public health and the environment from improperly designed or constructed sewage disposal systems, an OWTS must be designed by a Registered Civil Engineer (RCE), Professional Geologist (PG), or a Registered Environmental Health Specialist (REHS). When proposing a repair to an existing OWTS, a design by a registered professional may not be required.
How long does it take to get my OWTS plans approved?
The time required to review an OWTS design is approximately 3 to 4 weeks and depends on the number of applications that were submitted before your application. Additional time may be required if the application package submitted is incomplete or if there are deficiencies in the information contained in the soil engineering report.
What size OWTS is required for a remodel of an existing house or for a proposed new residence?
Septic tank capacity requirements are based on the number of bedroom equivalents and the number of plumbing fixture units. Disposal field dimensions are based on percolation rates.
See Bedroom Equivalent, Fixture Unit Worksheet, and Residential Septic Tank Size Chart.
How much does it cost to submit an application for an OWTS design review?
The fees charged for processing applications for a new OWTS, certification of an existing OWTS, and a permit to construct an OWTS are established by the Ventura County Board of Supervisors.
See OWTS Fees
Who will do the plan check and inspection of my OWTS application?
There are currently two staff assigned to do all OWTS plan check and inspections.
The following map depicts the the geographical areas served by each of the Environmental Health Specialists: OWTS District Map.
After my OWTS plans are approved, what should I do?
After design approval of an Application for New OWTS is received, submit one copy of the approved plans to the Ventura County Building and Safety Division for the issuance of your building permit.
When do I need an OWTS construction permit?
OWTS construction permits are required for the construction of any new system or the repair of an existing system. Repair of an existing system means abandoning an old tank and/or disposal field and installing a new one in its place.
What phone number do I call for an OWTS inspection?
Call the OWTS inspection hotline at (805) 477-7136. Be prepared to leave the following information: name, phone number, job address, owner name as listed on the permit, and date inspection is requested. If you need to cancel an inspection, call this number as soon as possible.
When do I call for the first inspection on my OWTS?
Who is licensed to install an OWTS?
A contractor with a valid “A” (Engineering), “C-32” (Plumbing), or “C-42” (Sanitation Systems) license from the state of California is allowed to install an OWTS.
Can I install my own OWTS?
An owner-builder can install his own OWTS. However, the Environmental Health Division highly recommends hiring a licensed and experienced contractor to do the work. Those not experienced in OWTS installation often make mistakes that lead to thousands of dollars in extra costs.
What is the proper disposal field rock to use in the construction of an OWTS?
See OWTS Drain Rock Notice public information handout for more information on the type of drain rock required, as well as drain rock inspection and approval.
Can I use a plastic leaching chamber instead of a rock-filled trench for my leach lines?
Yes, IAPMO (International Association of Plumbing and Mechanical Officials) listed plastic leaching chambers are approved for use in Ventura County. The size and type of plastic chamber must be specified in the soils report submitted with an application for a new OWTS.
Does the Environmental Health Division “certify” septic systems for the purpose of lender approvals during a real estate transaction?
No, the Environmental Health Divsion only certifies an existing OWTS when either a setback certification or full certification is required to obtain a building permit for construction purposes.
What is meant by a “setback”?
A setback is a horizontal distance, unobstructed and open to the sky, between a specified component of an OWTS and another object specified in the setback chart.
What are the required OWTS setback distances?
See Setback Chart
I’ve been told to expose a corner of my septic tank and call for an inspection; why do I need to dig up my septic tank?
During the course of processing a Setback or Full Certification of an OWTS it is often necessary to precisely locate a component of an OWTS. Inspection of the septic tank and/or other component of the OWTS will verify that minimum setback distances are maintained. If, for example, you were constructing a swimming pool, you might be required to mark off the location of the proposed pool and expose the septic tank for inspection. The inspection will determine if the required minimum 5′ horizontal distance between the proposed pool structure and the septic tank is maintained.
