Cal. Pub. Util. Code § 2705.6

(a)
1. (1) A mobilehome park that provides water service only to its tenants from water supplies and facilities that it owns, not otherwise dedicated to public service, is not a water corporation. However, if a complaint is filed with the commission by tenants of the mobilehome park that represent 10 percent or more of the park’s water service connections during any 12-month period, claiming that the water rates charged by the park are not just and reasonable or that the service is inadequate, the commission shall have jurisdiction to determine the merits of the complaint and shall determine, based on all the facts and circumstances, whether the rates charged are just and reasonable and whether the service provided is adequate.
2. (2) The numerical threshold of persons may include former or current tenants, or both.
3. (3) A person shall not file a complaint against a mobilehome park pursuant to paragraph (1) if that person has not resided in that mobilehome park within the last five years.
(b) Complaints filed pursuant to subdivision (a) are subject to this code and to the Rules of Practice and Procedure of the commission governing complaints and commission investigations.
(c)
1. (1) A mobilehome park, as described in subdivision (a), shall provide written notice to each of the mobilehome park’s tenants to inform those tenants of their right to, and how to, file a complaint with the commission about the water rates charged or the service provided by the mobilehome park. With respect to the notice, the mobilehome park shall do all of the following:
  1. (A) Provide the notice to new tenants at the time the tenants establish residence within the mobilehome park.
  2. (B) Provide the notice to tenants each time the mobilehome park changes water rates or service.
2. (2)
  1. (A) Notwithstanding any other law, the notice provided by a mobilehome park pursuant to paragraph (1) shall be written in English, the languages set forth in subdivision (b) of Section 1632 of the Civil Code, and the language or languages of primary communication with the residents receiving the notice.
  2. (B) The commission shall prepare and make available on its Internet Web site an approved notice in English and the languages set forth in subdivision (b) of Section 1632 of the Civil Code. In providing notice pursuant to paragraph (1), a mobilehome park shall use the then-current language made available by the commission pursuant to this subparagraph.
3. (3) A mobilehome park that fails to provide the notice required by this subdivision shall be subject to the penalties established in Section 2111.
(d) The commission may afford rate relief or may order the mobilehome park to improve its water supply, facilities, and services on those terms that it finds just and reasonable, or both.
(e) If the commission finds, after investigation, that the mobilehome park has charged an unjust or unreasonable rate in violation of this section subsequent to December 31, 2012, the commission shall order the mobilehome park to reimburse the complainants and any other current and former tenants affected by the rate, if no discrimination will result from the reimbursement. Reimbursement shall be calculated from the first date of collection of the unjust or unreasonable rate, with interest. The commission shall not make an order for the payment of reimbursement upon the ground of unjustness or unreasonableness if the rate in question has been previously declared by formal finding of the commission to be reasonable. The commission shall not recognize the assignment of a reimbursement claim except assignments by operation of law as in cases of death, insanity, bankruptcy, receivership, or order of court.
(f) The public advisor created pursuant to Section 321 and necessary staff of the commission shall assist the complainants.