Pub. Util. Code, § 454

(a) Except as provided in Section 455, a public utility shall not change any rate or so alter any classification, contract, practice, or rule as to result in any new rate, except upon a showing before the commission and a finding by the commission that the new rate is justified. Whenever any electrical, gas, heat, telephone, water, or sewer system corporation files an application to change any rate, other than a change reflecting and passing through to customers only new costs to the corporation which do not result in changes in revenue allocation, for the services or commodities furnished by it, the corporation shall furnish to its customers affected by the proposed rate change notice of its application to the commission for approval of the new rate. This notice requirement does not apply to any rate change proposed by a corporation pursuant to an advice letter submitted to the commission in accordance with commission procedures for this means of submission. The procedures for advice letters may include provision for notice to customers or subscribers on a case-by-case basis, as determined by the commission. The corporation may include the notice with the regular bill for charges transmitted to the customers within 45 days if the corporation operates on a 30-day billing cycle, or within 75 days if the corporation operates on a 60-day billing cycle. If more than one application to change any rate is filed within a single billing cycle, the corporation may combine the notices into a single notice if the applications are separately identified. The notice shall state the amount of the proposed rate change expressed in both dollar and percentage terms for the entire rate change as well as for each customer classification, a brief statement of the reasons the change is required or sought, and the mailing, and if available, the email address of the commission to which any customer inquiries may be directed regarding how to participate in, or receive further notices regarding the date, time, or place of, any hearing on the application, and the mailing address of the corporation to which any customer inquiries relative to the proposed rate change may be directed.

(b) For a water corporation with more than 2,000 service connections, the notice required in subdivision (a) shall include estimated rate impacts on the various customer classes of the corporation. The commission may require the corporation to inform customers in a separate letter or through a bill insert, at the corporation’s discretion, of the outcome of the general rate case, within 60 days if the corporation operates on a 30-day billing cycle, or within 90 days if the corporation operates on a 60-day billing cycle, of the commission’s final decision, including the approved rates and the approved capital projects that will subsequently be executed by way of an advice letter.

(c) The commission may adopt rules it considers reasonable and proper for each class of public utility providing for the nature of the showing required to be made in support of proposed rate changes, the form and manner of the presentation of the showing, with or without a hearing, and the procedure to be followed in the consideration thereof. Rules applicable to common carriers may provide for the publication and filing of any proposed rate change together with a written showing in support thereof, giving notice of the filing and showing in support thereof to the public, granting an opportunity for protests thereto, and to the consideration of, and action on, the showing and any protests filed thereto by the commission, with or without hearing. However, the proposed rate change does not become effective until it has been approved by the commission.

(d) The commission shall permit individual public utility customers and subscribers affected by a proposed rate change, and organizations formed to represent their interests, to testify at any hearing on the proposed rate change, except that the presiding officer need not allow repetitive or irrelevant testimony and may conduct the hearing in an efficient manner.