Cal. Code Regs. tit. 22, § 60351 – Filtration.

(a) Alarm and multiple filter units capable of treating the entire flow with one unit not in operation.
(b) Alarm, short-term retention or disposal provisions and standby replacement equipment.
(c) Alarm and long-term storage or disposal provisions.
(d) Automatically actuated long-term storage or disposal provisions.
(e) Alarm and standby filtration unit process.

All filtration unit processes shall be provided with one of the following reliability features: