# High Hazard Backflow Preventer: CA Requirements > A high hazard backflow preventer in California is an air gap or RP. See CCCPH degree-of-hazard rules, allowed assemblies, and the full Appendix D list. Source: https://www.exoduswater.com/post/high-hazard-vs-low-hazard-cross-connections Cross-connection & backflow October 30, 2026Exodus Water Services # High Hazard vs. Low Hazard Cross Connections: Which Backflow Preventer Is Required? A high hazard backflow preventer in California is an air gap or RP. See CCCPH degree-of-hazard rules, allowed assemblies, and the full Appendix D list. **Short answer:** In California, a high hazard cross connection must be protected by an **air gap (AG)** or a **reduced pressure principle backflow prevention assembly (RP)** , installed as premises containment at the customer’s service connection, unless the State Water Board handbook provides otherwise (CCCPH Section 3.2.2(c)). A low hazard cross connection can be protected by a **double check valve assembly (DC)** or anything more protective, and the double check family is limited to low hazard use (CCCPH Section 3.1.1). The degree of hazard is set by the water system’s hazard assessment, and Appendix D of the Cross-Connection Control Policy Handbook (CCCPH) lists 40 types of premises that are high hazard by default. _Last reviewed October 30, 2026, against the April 21, 2026 revision of the CCCPH. Sources are listed at the end._ ## What does “degree of hazard” mean? Every hazard assessment under the CCCPH must classify a premises in one of three ways (Section 3.2.1(b)): | Degree of hazard | CCCPH definition (Section 3.1.1) | What can enter the water | | ---------------- | -------------------------------------------------------------------------------------------------------------------------- | -------------------------------- | | **High hazard** | A cross connection that poses a threat to the potability or safety of the public water supply | Contaminants or health hazards | | **Low hazard** | A cross connection that does not threaten potability or safety but may adversely affect the aesthetic quality of the water | Pollutants or non-health hazards | | **No hazard** | No cross connection hazard identified | None | The assessment must also decide whether any existing assembly gives adequate protection for that degree of hazard (Section 3.2.1(c)), and the assembly installed must be “no less protective” than the hazard requires (Section 3.2.2(b)). The hazard drives the assembly. ## Which backflow preventer is required for a high hazard? Section 3.2.2(c) requires a water system to protect its distribution system from high hazard cross connections **at all times** , through **premises containment** , using **AGs or RPs** . Where the handbook names an RP, an RPDA or RPDA-II may be substituted if appropriate (Section 3.2.2(a)). There are two approval-based exceptions: - **Alternate method instead of a required air gap.** After State Water Board review and approval, a water system may use an alternate containment method if it does not increase risk to public health (Section 3.2.2(c)(1)). - **Internal protection instead of containment.** After State Water Board review and approval, a water system may accept internal protection when premises containment is not feasible (Section 3.2.2(c)(2)). Some Appendix D items are stricter and require an **air gap only** (marked (+) in the list below). Recycled water use areas can use a swivel-ell instead of an air gap during temporary potable supply, if every condition in Section 3.2.2(d) is met. ## Which backflow preventer is allowed for a low hazard? The CCCPH does not publish a low hazard list. Instead, it limits certain assemblies to low hazard use: | Assembly | Allowed for | CCCPH reference | | ---------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------- | -------------------- | | Air gap (AG) | Any degree of hazard; the highest level of protection | 3.1.1, 3.3.1(a) | | Reduced pressure principle (RP, RPDA, RPDA-II) | High or low hazard; backpressure and backsiphonage | 3.1.1, 3.2.2(a), (c) | | Double check valve (DC, DCDA, DCDA-II) | **Low hazard only** | 3.1.1 | | Pressure vacuum breaker (PVB) | Backsiphonage only, never backpressure; containment only for roadway right-of-way irrigation with no backpressure potential | 3.1.1, 3.3.2(e) | | Spill-resistant vacuum breaker (SVB) | Backsiphonage only; never for premises containment | 3.1.1, 3.3.2(e) | Two rules for fire protection systems connect the two categories (Section 3.2.2(e)): - Every user premises with a fire protection system must have **at least DC protection** within ten years of the CCCPH effective date of July 1, 2024\. Water systems with existing fire systems that cannot meet that date may propose an alternative date or method in their plan. - A **high hazard fire protection system** , including one that uses chemical additives such as wetting agents, foam, antifreeze, or corrosion inhibitor, or one with an auxiliary water supply, must have **at least RP protection** . - A low hazard fire system on a residential premises needs no assembly if it meets all five conditions in Section 3.2.2(e)(3), including a single service connection, a single meter, NSF/ANSI 61 piping, and looped piping tied to a routinely used fixture. ## Which premises are high hazard under Appendix D? Appendix D lists premises that require an AG or an RP “unless noted otherwise.” The list is not all-inclusive: a water system, the State Water Board, or a local health agency can require an AG, an RP, or both for other hazards found during a hazard assessment. A water system may also reduce or increase the minimum protection for a premises after a hazard reassessment under Section 3.2.1. Here is the full list as it stands in the April 2026 revision, grouped for reading. The original item numbers are kept, because many Cross-Connection Control Plans cite them by number. | Category | Appendix D items | | ---------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Wastewater and sewage | 1\. Sewage handling facilities; 2\. Wastewater lift stations and pumping stations; 3\. Wastewater treatment processes, handling, or pumping equipment interconnected to piping connected to a PWS **(+)** | | Energy, chemicals, radioactive materials | 4\. Petroleum processing or storage plants; 5\. Radioactive material storage, processing plants, or nuclear reactors; 18\. Chemical plants | | Death care | 6\. Mortuaries; 7\. Cemeteries | | Water supply and service configuration | 8\. Sites with an auxiliary water supply **(+-+)** ; 9\. Deleted; 10\. Premises with more than one connection to the PWS **(++++)** ; 39\. Private water distribution mains; 40\. Drinking water storage tank overflow connected to a sump or storm drain **(+)** | | Recycled water and graywater | 11\. Recycled water **(++)(+++)** ; 12\. Recycled water interconnected to piping that contains water from a PWS **(+)** ; 13\. Graywater systems, as defined in Water Code Section 14876, interconnected to piping connected to a PWS | | Health care | 14\. Medical facilities; 15\. Kidney dialysis facilities; 16\. Dental office with water-connected equipment; 17\. Veterinarian facilities | | Labs and manufacturing | 19\. Laboratories; 20\. Biotech facilities; 21\. Electronics manufacture; 24\. Metal-plating facilities | | Commercial services | 22\. Dry cleaner facilities; 23\. Industrial or commercial laundry facilities; 27\. Car wash facilities; 29\. Hotels/motels; 30\. Gas stations; 33\. Pet groomers | | Multi-tenant and lodging | 25\. Business park with a single meter serving multiple businesses; 28\. Mobile home park, RV park, or campgrounds with RV hookups | | Transportation and public facilities | 26\. Marine-port facilities; 31\. Fire stations; 32\. Solid waste disposal facilities; 36\. Railroad maintenance facilities; 37\. Incarceration facilities (e.g., prisons); 41\. Airports | | Agriculture | 34\. Agricultural premises | | Access and temporary use | 35\. Hazard assessment access denied or restricted; 38\. Temporary connections to fire hydrants for miscellaneous uses, including construction | ### What the Appendix D symbols mean | Symbol | Meaning in the CCCPH | | ------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | (+) | Premises isolated by **air gap only** , except as allowed through Section 3.2.2(c) | | (++) | Dual-plumbed use areas established under Title 22, Sections 60313 through 60316 | | (+++) | Residences using recycled water for landscape irrigation in an approved dual-plumbed use area must use **at least a DC** . If the water supplier also supplies the recycled water, it may get approval for an alternative plan with annual inspections and an annual cross-connection test under Title 22, Section 60316(a), instead of an assembly | | (++++) | Every connection must get at least the same level of protection, excluding fire protection. If one connection needs an RP, all connections need RPs | | (+-+) | An existing DC installed before July 1, 2024 may stay in service under four conditions (see next section). New or replacement installations after July 1, 2024 must be an AG, an RP, or both | ## What changed for auxiliary water supplies in April 2026? The April 21, 2026 revision changed items 8 and 9\. Before it, Appendix D listed sites with an auxiliary water supply **interconnected** with the PWS as air gap only (item 8), and sites with an auxiliary water supply **not interconnected** with the PWS as a separate item (item 9). The revision merged them into a single item 8, “Sites with an auxiliary water supply,” and replaced item 9 with the word “Deleted” so that plans citing later item numbers stay correct. The new (+-+) footnote lets a premises keep an existing DC installed before July 1, 2024, only if all four conditions are met: 1. backflow does not occur at any time at the premises; 2. the DC passes all field tests within the testing and repair timeframe in the water system’s plan; 3. the water system approves the DC in writing and records its location; and 4. no other high hazard activities are found during a hazard assessment. The State Water Board’s change log explains that auxiliary supplies include private irrigation wells, private drinking water wells, rainwater collection systems, and backyard ponds, and that it treats them as high hazard because their water quality is usually unknown. It also states that the change does not allow DCs for premises newly identified as having an auxiliary supply, and does not allow an existing DC to be replaced with another DC. ## How do you decide whether a premises is high hazard? Appendix D is the starting point, not the whole answer. A certified cross-connection control specialist must review or conduct each initial and follow-up hazard assessment and make a written finding that the assessment identified all hazards, the right degree of hazard, and the corresponding protection (Section 3.2.1(h)). The assessment must consider eight factors, including materials on site, piping complexity, auxiliary supplies and pumps, distribution conditions, accessibility, and past incidents (Section 3.2.1(a)). Practical points: - **Access denied counts.** If a customer refuses or restricts access for an assessment, Appendix D item 35 makes the premises high hazard. - **Multiple connections raise every connection.** Under the (++++) note, a premises with one RP connection needs RPs on all of its non-fire connections. - **Changes trigger reassessment.** A community water system must reassess when an account holder changes (excluding single-family homes), when activities or materials change, after backflow, or on the periodic interval in its plan (Section 3.2.1(e)). For the full assessment process, see [CCCPH hazard assessments: what water systems must do](https://www.exoduswater.com/post/cccph-hazard-assessments-what-water-systems-must-do) . ## How often are high hazard assemblies tested? At least once a year, and after installation, repair, depressurization for winterizing, or permanent relocation, by a certified tester (Section 3.3.3(a), (b)). The handbook allows a water system, the State Water Board, or a local health agency to require **more frequent testing** for premises with a high hazard cross connection or an assembly at increased risk of failure (Section 3.3.3(b)). A failed assembly must be repaired or replaced within 30 days of notice (Section 3.3.3(e)). Our [backflow testing guide](https://www.exoduswater.com/post/backflow-testing-california-property-owner-guide) covers the owner’s side. ## Related reading - [What is a cross connection?](https://www.exoduswater.com/post/what-is-a-cross-connection) - [Containment vs. isolation backflow protection](https://www.exoduswater.com/post/containment-vs-isolation-backflow-protection) - [The CCCPH explained](https://www.exoduswater.com/post/cccph-explained) - [Cross-connection control plan checklist](https://www.exoduswater.com/post/cross-connection-control-plan-checklist-california) ## How Exodus helps Exodus Water Services, based in Thousand Oaks, runs [cross-connection control programs](https://www.exoduswater.com/cross-connection-control) for public water systems across [California](https://www.exoduswater.com/california-coverage) . Our certified Cross-Connection Control Specialists classify each premises against Appendix D and the Section 3.2.1 factors, and the finding, required assembly, and test history live in one record in [Exodus Water Compliance](https://www.exoduswater.com/exodus-water-compliance) . See our [proven work](https://www.exoduswater.com/services#proven-work) . ## Frequently asked questions **What is a high hazard backflow preventer?**In California it is an air gap or a reduced pressure principle assembly (RP, RPDA, or RPDA-II). Those are the methods Section 3.2.2(c) of the CCCPH allows for high hazard premises containment, unless the handbook provides otherwise. **Can a double check valve be used for a high hazard?**Generally no. The CCCPH limits the DC, DCDA, and DCDA-II to low hazard cross connections. Appendix D notes two exceptions: an existing DC at an auxiliary water supply site, installed before July 1, 2024, that meets all four (+-+) conditions, and residences irrigating with recycled water in an approved dual-plumbed use area, which must use at least a DC under the (+++) note. **Is a reduced pressure assembly enough for every high hazard?**No. Appendix D items marked (+) require an air gap only: wastewater equipment interconnected with the water system, recycled water interconnected with potable piping, and storage tank overflows connected to a sump or storm drain, unless the State Water Board approves an alternative under Section 3.2.2(c). **What is an example of a low hazard cross connection?**The CCCPH does not list low hazard premises. A low hazard cross connection is one that could affect the aesthetic quality of the water without threatening health. The water system’s hazard assessment decides the classification. **Do fire sprinkler systems need an RP?**Only if they are high hazard, such as systems with chemical additives or an auxiliary water supply. Other fire systems need at least a DC within ten years of July 1, 2024, and some low hazard residential systems need no assembly (Section 3.2.2(e)). **What happens if a customer will not allow a hazard assessment?**Appendix D item 35 lists “hazard assessment access denied or restricted” as high hazard, so the premises would need an AG or RP. Last reviewed: October 30, 2026. ## Sources - State Water Board, [Cross-Connection Control Policy Handbook page](https://www.waterboards.ca.gov/drinking%5Fwater/certlic/drinkingwater/cccph.html) - State Water Board, [Cross-Connection Control Policy Handbook, April 2026 revision (PDF)](https://www.waterboards.ca.gov/drinking%5Fwater/certlic/drinkingwater/docs/2026/cross-connection-control-policy-handbook-apr-2026.pdf) : Sections 3.1.1, 3.2.1, 3.2.2, 3.3.2, 3.3.3, and Appendix D - State Water Board, [Changes to the CCCPH, April 2026 change log (PDF)](https://www.waterboards.ca.gov/drinking%5Fwater/certlic/drinkingwater/docs/2026/april-2026-change-log.pdf) : Appendix D items 8 and 9 - State Water Board, [Cross-Connection Control Policy Handbook as adopted December 19, 2023 (PDF)](https://www.waterboards.ca.gov/drinking%5Fwater/certlic/drinkingwater/docs/2023/cccph-adopt.pdf) : original Appendix D items 8 and 9 Need a second look at how your system classifies high hazard premises? 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