Cal. Water Code § 10609.22

(a) An urban retail water supplier shall calculate its actual urban water use no later than January 1, 2024, and by January 1 every year thereafter.
(b) The calculation shall be based on the urban retail water supplier’s water use for the previous calendar or fiscal year.
(c) Each urban water supplier’s urban water use shall be composed of the sum of the following:
1. (1) Aggregate residential water use.
2. (2) Aggregate outdoor irrigation of landscape areas with dedicated irrigation meters in connection with CII water use.
3. (3) Aggregate water losses.