Cal. Code Regs. tit. 17, § 12520 – Areas, Equipment, and Operations to Be Sanitary.

(a) Areas, equipment, and utensils used for preparing, storing or otherwise handling any food product and all other parts of the establishment shall be kept clean and in sanitary condition.
Areas in which any food product is prepared, processed, stored or handled, including walls, ceilings, and overhead structures of such areas shall be kept as reasonably free from moisture as is practicable. In such areas there shall be no drippings from any source including ceilings and overhead structures that may contaminate the product.
(b) Equipment and utensils used for preparing, processing, or otherwise handling any food product shall be of such materials and construction that they can be readily and thoroughly cleaned. Pipe lines used to convey fluid or semifluid products shall be so constructed that they can be readily and thoroughly cleaned.
(c) Operations and procedures involving the preparation, storing, or handling of any food product shall be strictly in accord with good sanitary practice.