The programme of analyses of water samples taken from production and distribution facilities may be modified by the Director General of the Regional Health Agency, on his own initiative or at the request of the Prefect, and in accordance with the procedures laid down by the Ministerial Order referred to in article R. 1321-15, if the conditions for the protection of the water catchment and the operation of the facilities, the checks carried out and the quality of the water so require or allow.