Indirect Potable Reuse Information
Indirect Potable Reuse (IPR) is the planned use of recycled water to replenish drinking water supplies with a suitable environmental barrier. There are two types of IPR projects: Groundwater Replenishment Reuse Projects (GRRP) and Surface Water Source Augmentation Projects (SWSAP).
A GRRP is a project involving the planned use of recycled municipal wastewater that is operated for the purpose of replenishing a groundwater basin designated in the Water Quality Control Plan [as defined in Water Code section 13050(j)] for use as a source of municipal and domestic water supply. There are two types of GRRPs: surface application, where the recharge water is applied to a spreading area, and subsurface application, where the recharge water is applied by other means.
Regulations for GRRPs became effective on June 18, 2014 and are included in Articles 5.1 and 5.2 of the Water Recycling Criteria, Title 22, Division 4, Chapter 3 of the California Code of Regulations.
Surface Water Augmentation
A SWSAP is a project involving the planned placement of recycled municipal wastewater into a surface water reservoir that is used as a source of domestic drinking water supply, for the purpose of supplementing the source of domestic drinking water supply.
Regulations for SWSAPs became effective on October 1, 2018 and are included in Article 5.3 of the Water Recycling Criteria, Title 22, Division 4, Chapter 3 of the California Code of Regulations.
Guidance and Reports
- Preparation of an Engineering Report for the Production, Distribution and Use of Recycled Water — June 2023
- Alternative Treatment Technology Report for Recycled Water (April 2023) (PDF)
- Appendix A. California Department of Health Services Reduction of Virus and Bacteria by Filtration and Disinfection (October 2001) (PDF)
- Appendix B. Advisory Memo Concerning the Cleaning of UV Quartz Sleeves (PDF)
- Appendix C. Historic Conditionally Accepted Granular Media Filters (PDF)
- Appendix D. Pre-2013 Historic Conditionally Accepted Polymeric Membrane Filters (Post-2013 Polymeric Membranes no longer need to be Conditionally Accepted) (PDF)
- Appendix E. Available Conditional Acceptance Letters Referenced in the ATTR (PDF)