the supply of drinking water and waste water in the territory of the municipalities belonging to the special-purpose association. It shall operate, maintain and, if necessary, expand and improve the existing facilities required for this purpose, as well as plan, build, acquire, operate and maintain the additionally required water supply and sewage disposal facilities. Within the framework of the law, this also includes the establishment and maintenance of ancillary and auxiliary operations that promote the tasks of the waterworks and are economically related to them. Within the framework of the law, the waterworks may also be commissioned to perform the aforementioned tasks for municipalities not belonging to the special-purpose association.