The objective of the present study is to evaluate the purification processes of a public water vending machine company in Ciudad Juarez. A revision of the Osmonics Manual of Pure Water was carried out, as well as other bibliographical sources on line, in order to summarize the water purification methods and other information related to the topic. Information on water quality from the public distribution network in a site of the northern part of the city was obtained. This network is the water source for the drinking water machines. The information was obtained from the Environmental Laboratory of the Institute of Engineering and Technology (IIT) at the UACJ, in the period 2002-2004. Based on the processes required for water purification, a comparison with the technology utilized by the company was done and the evaluation was obtained. The results show that there is compatibility among the purification processes applied and the water quality supplied. Nevertheless, it is observed in the historic analysis of the water quality from the public distribution network that some parameters do not correspond with the standards (Phenols, Chlorides, Aluminum, Sodium and Mercury). Besides, the total dissolved solids of this water source (900 ppm) is above the standard in comparison with the one required for an optimum operation (650 ppm), according to Osmonics Co. It is concluded that the water quality provided by the company is good. It is recommended to carry out a study of water quality based on samplings of all the water machines of the company.