WAT §373: (a) Revenues derived from allocation-based conservation water pricing shall not exceed the reasonable cost of water service including basic costs and incremental costs.

(a) Revenues derived from allocation-based conservation water pricing shall not exceed the reasonable cost of water service including basic costs and incremental costs. This chapter does not limit the sources of funding for incremental costs to charges for water use. (b) Revenues derived from allocation-based conservation water pricing shall not exceed the proportional cost of service attributable to the customer’s parcel, as determined by giving consideration to all of the following: (1) Customer classes established in consideration of service characteristics, demand patterns, and other factors. (2) Basic use allocations. (3) Meter size. (4) Metered volume of water consumed. (5) The public entity’s discretionary allocation of incremental costs between and among the increments of water use subject to conservation charges, as permitted by paragraph (4) of subdivision (a) of Section 372 to meet the requirement of that section. (c) In establishing the schedule of charges and metered volumes for the increments of water use subject to conservation charges, the public entity may also consider both of the following: (1) Customer overuse characteristics, including ratios between overuse volumes and basic use allocations, variations in demand and consumption patterns, or other characteristics of overuse experienced by the public entity. (2) The extent to which the pricing structure of the increments will be effective in minimizing or eliminating the need for other measures to curtail potential overuse.