Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS
1604.3 Equipment Room Signs — 2025 California Plumbing Code
California Plumbing Code (Title 24, Part 5) · 2025 edition · updated 2026-09-25 · California
CBSC: official editions, supplements and errata
Italicized text is a California amendment to the model code, as printed in the official publication.
Cite as: 2025 California Plumbing Code (Title 24, Part 5) § 1604.3 · Effective January 1, 2026 · Official source: Building Standards Commission
Each equipment room containing nonpotable rainwater equipment shall have a sign posted with the following wording in 1 inch (25.4 mm) let ters:
NONPOTABLE RAINWATER CATCHMENT SYSTEMS
(3) Fixtures, potable, and rainwater shall be tested and inspected for flow. Flow from a rainwater catchment water system outlet shall indicate a cross-connection. No flow from a potable water outlet shall indicate that it is connected to the rainwater system.
(4) The drain on the rainwater catchment water system shall be checked for flow during the test and at the end of the period.
(5) The potable water system shall then be completely drained.
(6) The rainwater catchment water system shall then be activated and pressurized. When rainwater is not available for the initial cross-connection test, a tem- porary connection to a potable water supply shall be required. At the conclusion of the initial cross- connection test, the temporary connection to the potable water supply shall be disconnected.
(7) The rainwater catchment water system shall remain pressurized for a minimum period of time specified by the Authority Having Jurisdiction while the potable water system is empty. The minimum period the potable water system is to remain depressurized shall be determined on a case-by-case basis, but in no case shall that period be less than 1 hour.
(8) Fixtures, potable and rainwater catchment, shall be tested and inspected for flow. Flow from a potable water system outlet shall indicate a cross-connection. No flow from a rainwater catchment water outlet shall indicate that it is connected to the potable water system.
(9) The drain on the potable water system shall be checked for flow during the test and at the end of the period.
(10)Where there is no flow detected in the fixtures which would indicate a cross-connection, the potable water system shall be repressurized. 1605.3.3 Discovery of Cross-Connection. In the event that a cross-connection is discovered, the following procedure, in the presence of the Authority Having Jurisdiction, shall be activated immediately:
(1) Rainwater catchment piping to the building shall be shutdown at the supply source(s), and the rainwater riser shall be drained.
(2) Potable water piping to the building shall be shutdown at the meter.
(3) The cross-connection shall be uncovered and disconnected.
(4) The building shall be retested following procedures listed in Section 1605.3.1 and Section 1605.3.2.
(5) The potable water system shall be chlorinated with 50 ppm chlorine for 24 hours.
(6) The potable water system shall be flushed after 24 hours, and a standard bacteriological test shall be performed. Where test results are acceptable, the potable water system shall be permitted to be recharged.
332 2025 CALIFORNIA PLUMBING CODE
CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE
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