Onsite Wastewater Treatment Systems
DISCLAIMER: All guidance materials posted on this website are intended to provide the regulated community and the public with a general understanding of the OWTS Policy from a staff perspective. These materials are informational only, and are not intended to implement, interpret, or create new requirements. In the case of any conflict with existing statutes, regulations, or orders, the actual statute, regulation, or order governs. For specific questions, please contact staff of the State Water Board or the appropriate Regional Water Quality Control Board (Regional Water Board).
Technical Resources
United States Environmental Protection Agency (USEPA):
- Septic Systems (Onsite/Decentralized Systems) home page
- Technical Information about Septic Systems (links)
- Decentralized Wastewater Systems Technology Fact Sheets (algunos folletos informativos están disponibles en Español)
- Onsite Wastewater Treatment Systems Manual (2002)
- Onsite Wastewater Treatment and Disposal Systems (1980)
California Code of Regulations, Title 24, Part 5 (California Plumbing Code):
International Association of Plumbing and Mechanical Officials (IAPMO) Product Certification:
NSF OWTS Standards and Protocols:
- NSF Onsite Wastewater Treatment Systems
- NSF/ANSI 46: Wastewater Treatment System Components and Devices
- NSF/ANSI 245: Nitrogen Reduction
Contractor Licenses:
- Contractor State Licensing Board
- Hiring a Licensed Contractor
- License Check
- Licensed General Engineering Contractor (Class A)
- General Building Contractor (Class B)
- Sanitation System Contractor (Specialty Class C-42)
- Plumbing Contractor (Specialty Class C-36)
- California Code of Regulations, Article 3, Division 8, Title 16
- Business and Professions Code, Chapter 9
Alternative Collection and Disposal Systems
2023 OWTS Policy definitions include: “Onsite wastewater treatment system(s)” (OWTS) “means individual disposal systems, community collection and disposal systems, and alternative collection and disposal systems that use subsurface disposal. The short form of the term may be singular or plural. OWTS do not include “graywater” systems pursuant to Health and Safety Code Section 17922.12.”
2023 OWTS Policy Section 9.0, “The Local Agency Management Program for minimum OWTS Standards is a management program where local agencies can establish minimum standards that are differing requirements from those specified in Tier 1 (Section 7 and Section 8), including the areas that do not meet those minimum standards and still achieve this Policy’s purpose. Local Agency Management Programs may include any one or combination of the following to achieve this purpose:
- Differing system design requirements; including but not limited to, alternative collection and disposal systems that use subsurface disposal;
- Differing siting controls such as system density and setback requirements;
- Requirements for owners to enter monitoring and maintenance agreements;
and/or
- Creation of an onsite management district or zone.”
Alternative collection and disposal systems included by a local agency in an OWTS Policy Tier 2 LAMP must comply with the Policy conditions and meet the purpose of protecting water quality. The following links include information about alternative collection and disposal systems and technologies that may be a helpful resource.
