1.5 California Waterworks Standards (Title 22, Chapter 16)

Why This Chapter of Title 22 Matters

The SWRCB Expected Range of Knowledge for Drinking Water Treatment Exam lists California Waterworks Standards as an explicit sub-topic inside the Safety / Regulations / Administrative Duties category - the category that carries 15 questions at T1-T3 and 35 questions at T4. On the distribution side, the same material feeds the Drinking Water Regulations / Management / Safety category (15, 10, 15, 35, and 45 questions at D1 through D5). Very little else in the blueprint delivers as many crisp, numeric, memorizable answers.

The Waterworks Standards live in Title 22, CCR, Division 4, Chapter 16 (sections 64551-64644). The chapter was substantially rewritten effective March 9, 2008, which repealed most of old Article 8 (sections 64610 through 64644 - pumping stations, water main materials, main layout, minimum diameter, valve locations, hydrants, blowoffs, service connection pipe) and moved those requirements into Article 4. Prep material that still cites section 64624 or 64640 is quoting repealed law.

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Source Capacity (64554)

At all times, a public water system's water sources shall have the capacity to meet the system's maximum day demand (MDD). This must be satisfied system-wide and within each individual pressure zone - a common exam distinction, because a system can be adequate in aggregate and deficient in one zone.

• Systems with 1,000 or more service connections must be able to meet four hours of peak hourly demand (PHD) using source capacity, storage, or emergency connections.
• Systems with fewer than 1,000 service connections must have storage capacity equal to or greater than MDD, unless they can demonstrate additional supply sources or emergency connections that meet the requirement.

Determining MDD and PHD

Community water systems using only groundwater must have a minimum of two approved sources before an initial permit is granted, and must be able to meet demand with the highest-capacity source out of service - the "largest source offline" rule.

[!TIP] If a question gives you only an annual total, use the 2.25 factor, not 1.5. The regulation deliberately penalizes systems that have not metered themselves well enough to know their real peak day.

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New Wells (64560)

Before construction, the water system submits a technical report containing a source water assessment, documentation of a 50-foot protective zone around the well site, design plans and well specifications, and CEQA compliance documentation. After construction, the system provides local well construction permits, the Department of Water Resources completion report, pump test results, water quality analyses, and as-built plans.

New public wells must comply with DWR Bulletins 74-81 and 74-90 and AWWA Standard A100-06. Two specific construction details recur on exams: the wellhead terminates a minimum of 18 inches above finished grade, and the well must be equipped for chlorination, with non-threaded sampling taps and backflow protection.

Water Main Materials, Separation, Size, and Valves (Article 4)

Separation from Sewers (64572)

This is the highest-yield numeric rule in the chapter.

All separation distances are measured from the nearest outside edge of each pipe barrel - not centerline to centerline. Candidates who measure from centerlines get separation problems wrong.

Minimum Main Size (64573)

Newly installed water mains in a community water system shall have a nominal diameter of at least four inches. That is the entire state minimum. Local fire codes and the fire marshal routinely require 6 or 8 inches for hydranted mains, but the Title 22 floor is 4 inches - know the difference between the state minimum and a local requirement.

Isolation Valves (64577)

At a minimum, isolation valves shall be installed on all new water mains:

1. No farther than 1,320 linear feet apart on all mains 12 inches or less in diameter (1,320 feet is a quarter mile);
2. At each tee or crossing connection between mains 12 inches or less, within 100 feet of the tee or cross with the primary main; and
3. Between the water main and each fire hydrant served by the main.

Article 4 also covers air-release, air/vacuum, and combination valves (64576), flushing (64575), and water main valve construction (64578).

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Disinfection of New and Repaired Facilities (Article 5)

Article 5 works by incorporating AWWA standards by reference, which makes the AWWA numbers themselves testable California law:

[!IMPORTANT] Note the asymmetry. For mains, disinfection is mandatory before use and the sample must be coliform-negative. For wells, the trigger is reversed: you sample first, and disinfection under C654-03 is required only if coliform is detected. The three-month out-of-service threshold for wells is a favorite distractor.

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Distribution Reservoirs (64585)

Every distribution reservoir must satisfy four general requirements: coatings and linings installed per the manufacturer's instructions; vents and other openings constructed to exclude rainwater or runoff and birds, insects, rodents, or other animals; at least one sampling tap positioned to sample water entering the distribution system, freeze-protected as needed; and no design, construction, or use that creates a contamination hazard.

New reservoirs must additionally provide:

• Construction to AWWA tank standards (D100-05, D102-03, D103-97, D110-04, D120-02) of impervious material
• A rigid structural roof or a floating cover per AWWA guidance
• Separate inlet and outlet arranged to minimize short-circuiting
• Complete draining capability with overflow devices and no direct connection to a sewer
• Level monitoring, prevention of unauthorized access, and safe lighted access for inspection
• Isolation valves within 100 feet, with any bypass line used for disinfectant contact time blind-flanged during normal operation
• Protection from surface runoff, subsurface flow, and corrosion

Subsurface reservoirs carry extra duties: flooding prevention, 50-foot separation from sanitary sewers, groundwater monitoring wells, and specific design standards where a buried roof serves a secondary function such as a parking surface.

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Distribution System Operation (Article 8)

Minimum Pressure (64602)

Each distribution system shall be operated in a manner that assures the minimum operating pressure in the water main at the user service line connection throughout the distribution system is not less than 20 pounds per square inch at all times.

A separate, higher standard applies to major expansions: each new distribution system that expands existing service connections by more than 20 percent, or that may otherwise adversely affect distribution system pressure, shall be designed to provide a minimum operating pressure of not less than 40 psi at all times, excluding fire flow.

Two numbers, two different tests. 20 psi is an operating floor at all times including during fire flow; 40 psi is a design standard for qualifying new systems and excludes fire flow. Dropping below 20 psi is the trigger condition for a pressure-loss event that can require a precautionary boil water notice, because the main can draw contamination in through leaks and joints.

Article 8 also requires a Water System Operations and Maintenance Plan (64600) and the preparation and maintenance of records (64604).