Cal. Civ. Code § 1940.9

(a) If the landlord does not provide separate gas and electric meters for each tenant’s dwelling unit so that each tenant’s meter measures only the electric or gas service to that tenant’s dwelling unit and the landlord or his or her agent has knowledge that gas or electric service provided through a tenant’s meter serves an area outside the tenant’s dwelling unit, the landlord, prior to the inception of the tenancy or upon discovery, shall explicitly disclose that condition to the tenant and shall do either of the following:
(1) Execute a mutual written agreement with the tenant for payment by the tenant of the cost of the gas or electric service provided through the tenant’s meter to serve areas outside the tenant’s dwelling unit.
(2) Make other arrangements, as are mutually agreed in writing, for payment for the gas or electric service provided through the tenant’s meter to serve areas outside the tenant’s dwelling unit. These arrangements may include, but are not limited to, the landlord becoming the customer of record for the tenant’s meter, or the landlord separately metering and becoming the customer of record for the area outside the tenant’s dwelling unit.
(b) If a landlord fails to comply with subdivision (a), the aggrieved tenant may bring an action in a court of competent jurisdiction. The remedies the court may order shall include, but are not limited to, the following:
(1) Requiring the landlord to be made the customer of record with the utility for the tenant’s meter.
(2) Ordering the landlord to reimburse the tenant for payments made by the tenant to the utility for service to areas outside of the tenant’s dwelling unit. Payments to be reimbursed pursuant to this paragraph shall commence from the date the obligation to disclose arose under subdivision (a).
(c) Nothing in this section limits any remedies available to a landlord or tenant under other provisions of this chapter, the rental agreement, or applicable statutory or common law.