California Code, Penal Code - PEN § 4015

(a) The sheriff shall receive all persons committed to jail by competent authority.  The board of supervisors shall provide the sheriff with necessary food, clothing, and bedding, for those prisoners, which shall be of a quality and quantity at least equal to the minimum standards and requirements prescribed by the Board of Corrections for the feeding, clothing, and care of prisoners in all county, city and other local jails and detention facilities.  Except as provided in Section 4016, the expenses thereof shall be paid out of the county treasury.

(b) Nothing in this section shall be construed in a manner that would require the sheriff to receive a person who is in need of immediate medical care until the person has been transported to a hospital or medical facility so that his or her medical needs can be addressed prior to booking into county jail.

(c) Nothing in this section shall be construed or interpreted in a manner that would impose upon a city or its law enforcement agency any obligation to pay the cost of medical services rendered to any individual in need of immediate medical care who has been arrested by city law enforcement personnel and transported to a hospital or medical facility prior to being delivered to and received at the county jail or other detention facility for booking.

(d) It is the intent of the Legislature in enacting the act adding this subdivision to ensure that the costs associated with providing medical care to an arrested person are borne by the arrested person's private medical insurance or any other source of medical cost coverage for which the arrested person is eligible.