Cal. Water Code § 72072.10

The board shall enforce the provisions of this article and may prescribe, adopt and enforce rules and regulations relating to the administration and enforcement of this article. The board shall not prescribe, adopt or enforce any rule or regulation which has the effect, directly or indirectly, of altering the terms and conditions of service of a service supplier serving the general public. Rules and regulations prescribed and adopted by the board shall not be inconsistent with procedures established from time to time by a service supplier serving the general public for the purpose of billing, collecting and accounting for charges in the conduct of its business.