Cal. Health & Saf. Code § 116050
Except as provided in Section 18930, the department shall make and enforce regulations pertaining to public swimming pools as it deems proper and shall enforce building standards published in the State Building Standards Code relating to public swimming pools; provided, that no rule or regulation as to design or construction of pools shall apply to any pool that has been constructed before the adoption of the regulation, if the pool as constructed is reasonably safe and the manner of the construction does not preclude compliance with the requirements of the regulations as to bacteriological and chemical quality and clarity of the water in the pool. The department shall adopt and submit building standards for approval pursuant to Chapter 4 (commencing with Section 18935) of Part 2.5 of Division 13 for the purposes described in this section.
Ca. Health and Saf. Code § 116050