Approved laboratories and analytical procedures

All samples shall be examined by the department or by any other laboratory certified by the department for drinking water purposes, except that measurements for turbidity and free chlorine may be performed by any person deemed qualified by the department. Turbidity measurements shall be made by a nephelometric method approved by the department. All methods of sample preservation and analyses shall be as prescribed by the department and set forth under title 40 Code of Federal Regulations part 141.