A cross-connection is an interconnection between a potable water supply and a non-potable source via any actual or potential connection or structural arrangement between a public water system (PWS) and any source or distribution system containing liquid, gas, or other substances not from an approved water supply.

The presence of a cross-connection represents a location in a distribution system through which backflow of contaminants or pollutants can occur. Backflow is the undesired or unintended reversal of flow of water and/or other liquids, gases, or other substances into a PWS’s distribution system or approved water supply. Normally, water from the public water system flows only one way, into a water user’s premises. When backflow occurs, water from the consumer’s premises can be pushed or pulled into the distribution system. If that water has been contaminated because of activities on the consumer’s premises (for example, the use of chemicals for plating/etching metals, the addition of corrosion inhibitors to industrial boilers and piping, or fire suppression systems with chemical additives), the water can carry contaminants into the distribution system, possibly causing illness or even death. Public water systems are required by State law to have programs in place to detect cross-connections and prevent backflow.

The State of California recently made the most significant changes to the regulations since the 1980s by adopting the Cross-Connection Control Policy Handbook (CCCPH) on July 1, 2024. The primary objective of the CCCPH is the protection of public health through the establishment of standards intended to ensure that PWSs and their drinking water distribution systems will not be subject to backflow. The possibility of illness and disease occurring by means of unprotected cross-connections has been well established; the need to prevent cross-connections with auxiliary water supplies or contaminant sources was identified over 100 years ago. The risk posed by backflow can be mitigated through preventive and corrective measures. To protect our drinking water quality and prevent the spread of infectious disease and other contaminants, mechanical backflow prevention assemblies are utilized to prevent used, unclean or contaminated water or substances from entering the potable/domestic water system. To prevent contamination, it may be necessary to install testable backflow prevention assemblies to prevent backflow from occurring. In San Luis Obispo County, these assemblies must be tested every year by a backflow tester certified by an approved accrediting agency. The CCCPH and its standards apply to all California PWSs, as defined in California’s Health and Safety Code (CHSC, section 116275 (h)). Compliance with the CCCPH is mandatory for all California PWSs. In addition, the State Water Resources Control Board (State Water Board) intends to build a foundation of awareness within the regulated community regarding the importance of backflow protection and cross-connection control.

The County of San Luis Obispo Environmental Health Services division works with over two dozen PWSs to abate cross-connections and prevent backflow. In the coming months, your water purveyor may reach out to you to learn more about how you use your water. For instance, do you have a dedicated irrigation system, or do you have a fire sprinkler system? Your water system may also mail out flyers to educate consumers on backflow prevention and its role in protecting public health. These outreach efforts are part of the CCCPH requirement to inform consumers about the importance of cross-connection control and backflow prevention. Your cooperation with these outreach efforts is critical to the protection of public health and is greatly appreciated.

Cross-Connection Control Policy Handbook (CCCPH) | State Water Resources Control Board (ca.gov)
 

"Cross-connection" or "cross-connected" as used in these regulations means any real or potential connection between any part of a public water system or other water system supplying potable water to members of the public and any auxiliary water supply or any source or system containing water or any substance that is not or cannot be approved as safe, wholesome, and potable for human consumption.

Three things must happen in order for a backflow incident to occur:

1. An actual or potential cross-connection,
2. A non-potable water source is present,
3. Backpressure or a vacuum created within the plumbing.

An actual cross-connection is a cross-connection that is subject to both back-siphonage and backpressure.

A potential cross-connection is cross-connection that is subject to only back-siphonage (example, a garden hose extending into a swimming pool).

Backflow prevention assemblies are testable U.S.C. approved devices that are designed to prevent water from flowing back into a public water system.

The backflow prevention assembly should be installed as close to water meter as possible, as approved by the County of San Luis Obispo Environmental Health Services Division. Generally, the assembly should be no further than ten (10) feet from the water meter.

A “Lead Free” reduced pressure principle (RP) style backflow prevention assembly is required on domestic water service lines. RP style backflow prevention assemblies are also required on irrigation water service lines but are exempt from the “Lead Free” requirement. A Double Check or Double Check Detector Assembly are only allowed on fire sprinkler systems.

Approved backflow prevention assemblies

Yes, if a Water Department, Water Purveyor or the County Cross Connection Program required a backflow prevention assembly be installed, then you are required to test it at least annually per San Luis Obispo County Code of Ordinances Title 8 Chapter 8.30. 

• County of San Luis Obispo Certified Backflow Assembly Tester List

Yes, The Cross Connection Prevention Program will provide reminders forty five (45) days prior to the due date. Second due notices are sent out fifteen (15) days after the due date has elapsed. Final notice and recommendation that water services be terminated occurs thirty (30) days after the second notice has been mailed.

To request more information regarding your Backflow Prevention Assembly, have the service number of the assembly handy. The service number is a combination of the facility and device number and is represented by four numbers, a dash, then a three digit extension (example 9999-001) and is located in the upper right hand corner of the assembly test form.

Contact Matt Giuffrida at [email protected] or (805) 781-5567.