Cal. Gov't Code § 53082

(a) By July 1, 1991, local agencies shall refund any sewer service fees collected for which no services were delivered.
(b) Any sewer service fees collected by a local agency from any person for which no service has been provided shall be refunded in accordance with subdivisions (c) and (d).
(c) In cases where a person paid fees as described in subdivision (a) and is still residing at the same location, it shall be the responsibility of the local agency, upon determination that the premises is not connected to the sewer system, to return fees in their entirety, regardless of the amount of time the fees were wrongly collected. For the purposes of this section, if the exact amount of the charges is not readily available, the amount of the refund may be calculated by averaging the rates paid by payers in the same classification during the time period in which the fees were collected.
(d) In cases where a person paid fees as described in subdivision (a) but is not still residing at the same location, the payer of the fees may make a claim for a refund to the agency collecting the fees.
(e) No statute of limitations shall apply to claims for fees paid before January 1, 1992. For fees paid on or after January 1, 1992, claims shall be filed within 180 days of the date of payment.
(f) As used in this section, “sewer service fees” means periodic fees, tolls, rates, rentals, or other charges imposed by local agencies for the purpose of covering the cost to provide sewer service or to operate, maintain, repair, and replace sewer systems and facilities, but do not include any of the following:
1. (1) Sewer standby or availability charges or assessments.
2. (2) Special assessments levied in accordance with one or a combination of the Improvement Act of 1911 (Division 7 (commencing with Section 5000) of the Streets and Highways Code), the Municipal Improvement Act of 1913 (Division 12 (commencing with Section 10000) of the Streets and Highways Code), or the Improvement Bond Act of 1915 (Division 10 (commencing with Section 8500) of the Streets and Highways Code).
3. (3) Sewer connection charges or sewer capacity charges paid in conjunction with or as a condition of approving an application for sewer service.