Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS

1603.5 Minimum Water Quality. The minimum water

California Plumbing Code (Title 24, Part 5) · 2022 edition · updated 2026-09-10 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

quality for harvested rainwater shall meet the applicable water quality requirements for the intended applications as determined by the Authority Having Jurisdiction. In the absence of water quality requirements determined by the Authority Having Jurisdiction, the minimum treatment and water quality shall be in accordance with Table 1603.5. Exception: [BSC] No treatment is required for rainwater used for subsurface or nonsprinkled surface irrigation where the maximum storage volume is less than 5000 gallons (18 927 L) where the tank is supported directly upon grade and the ratio of height to diameter or width does not exceed 2 to 1.

1603.5.1 Treatment. If the quality of the tested water cannot consistently be maintained at the minimum levels specified in Table 1603.5, then the system shall be equipped

NONPOTABLE RAINWATER CATCHMENT SYSTEMS

with an appropriate treatment device meeting applicable NSF standards referenced in Chapter 17.

TABLE 1603.5 MINIMUM WATER QUALITY

APPLICATION	MINIMUM TREATMENT	MINIMUM WATER QUALITY
Car washing	Debris excluder or other approved means in accordance with Section 1603.18, and 100 microns_ (100 µm)_in accordance with Section 1603.19 for drip irriga- tion.	N/A
_Surface,_Subsurface and drip irrigation	Debris excluder or other approved means in accordance with Section 1603.18, and 100 microns_ (100 µm)_in accordance with Section 1603.19 for drip irriga- tion.	N/A
Spray irrigation where the maximum storage volume is less than 360 gallons_(1363 L)_	Debris excluder or other approved means in accordance with Section 1603.18, and disinfec- tion in accordance with Section 1603.16.	N/A
Spray irrigation where the maximum storage volume is equal to or more than 360 gallons (1363 L)	Debris excluder or other approved means in accordance with Section 1603.18.	Escherichia coli: < 100 CFU/100 mL, and Turbidity: < 10 NTU
Urinal and water closet flushing, clothes wash- ing, and trap priming	Debris excluder or other approved means in accordance with Section 1603.18, and 100 microns_(100 µm)_ in accordance with Section 1603.19.	Escherichia coli: < 100 CFU/100 mL, and Turbidity: < 10 NTU
Ornamental fountains and other water features	Debris excluder or other approved means in accordance with Section 1603.18.	Escherichia coli: < 100 CFU/100 mL, and Turbidity: < 10 NTU
Cooling tower make-up water	Debris excluder or other approved means in accordance with Section 1603.18, and 100 microns_ (100 µm)_in accordance with Section 1603.19.	Escherichia coli: < 100 CFU/100 mL, and Turbidity: < 10 NTU

1603.5.2 Disinfection. Where the initial quality of the collected rainwater requires disinfection or other treat- ment or both, the collected rainwater shall be treated as necessary to ensure the required water quality is deliv-

2022 CALIFORNIA PLUMBING CODE 323

(A) Animals and Insects. Screens installed on vent pipes,

inlets, and overflow pipes shall have an aperture of not greater than ¹ ∕ 16 of an inch (1.6 mm) and shall be close fit- ting. (B) Human Access. A minimum of one access opening shall

be provided to allow inspection and cleaning. Rainwater tank manholes and access openings shall be secured by either a lockable device or other approved method to pre- vent unauthorized access.