Individual Sewage Disposal System

Frequently Asked Questions

What is an Individual Sewage Disposal System?

An Individual Sewage Disposal System (ISDS) is a privately owned and maintained sewage disposal system. They are commonly referred to as septic systems or onsite wastewater treatment systems. All ISDS 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 ISDS: 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 designs my ISDS?

Due to the potential adverse impacts to public health and the environment from improperly designed or constructed sewage disposal systems, an ISDS 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 ISDS, a design by a registered professional may not be required.

How long does it take to get my ISDS plans approved?

The time required to review an ISDS 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 ISDS is required for a re-model 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 ISDS design review?

The fees charged for processing applications for a new ISDS, certification of an existing ISDS, and a permit to construct an ISDS are established by the Ventura County Board of Supervisors.

See ISDS Fees

Who will do the plan check and inspection of my ISDS application?

There are currently three staff assigned to do all ISDS plan check and inspections. The following map depicts the the geographical areas served by each of the Environmental Health Specialists: ISDS District Map

After my ISDS plans are approved what should I do?

After design approval of an Application for New ISDS 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 ISDS construction permit?

ISDS 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 ISDS inspection?

Call the ISDS 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 ISDS?

See ISDS Construction Procedures

Who is licensed to install an ISDS?

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 ISDS.

Can I install my own ISDS?

An owner-builder can install his own ISDS. However, the Environmental Health Division highly recommends hiring a licensed and experienced contractor to do the work. Those not experienced in ISDS 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 ISDS?

See Drain Rock Notice and ISDS Drain Rock picture below:

Can I use a plastic leaching chamber instead of a rock-filled trench for my leach lines?

Yes, IAMPO (International Association of Mechanical and Plumbing Offcials) 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 ISDS.

Does the Environmental Health Division "certify" septic systems for the purpose of lender approvals during a real estate transaction ?

No, the Enviromental Health Divsion only inspects an ISDS when an ISDS Permit to Construct is processed.

What is meant by a "setback"?

A setback is a horizontal distance, unobstructed and open to the sky, between a specified component of an ISDS and another object specified in the setback chart.

What are the required ISDS 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 ISDS it is often necessary to precisely locate a component of an ISDS. Inspection of the septic tank and/or other component of the ISDS 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.