California Code, Health and Safety Code - HSC § 111145

(a) The department shall require each bottler, distributor, or vendor of bottled water, each owner or operator of any water-vending machine, each water hauler, each retail water facility operator, each private water source operator, and each applicant for a license, to test for all substances necessary to establish conformance to standards adopted pursuant to Section 111080 at the times and frequencies the department may reasonably establish.

(b) Each product dispensed by a water-vending machine or a retail water facility shall be sampled and analyzed for coliform bacteria at least once every six months. The analysis shall be submitted to the department indicating whether the water is pure and wholesome. Analysis of vended water or water from retail water facilities shall be submitted to the local health officers if the local health officers are authorized by the department pursuant to subdivision (b) of Section 111105.

(c) Purified waters from retail water facilities shall be analyzed by the operator for dissolved solids by conductivity measurement not less frequently than once every seven days.

(d) Purified water from vending machines shall be analyzed by the operator for the dissolved solids by conductivity measurement each time the vending machine is serviced.