Background : Surveying drinking water quality, a priority for research subjects, seeks further attentions and their standards are determined according to the microbial, chemical, and physical quality as well as their applications. The microbial quality is measured by means of the presence of special pathogens. Thus in case of special pathogens presence we would consider the drinking water to be infected.

Materials and methods : This descriptive study was conducted to determine the quality of drinking water in Kashan city in 1999-2000. To meet this demand, Kashan was divided in 11 districts, then samples were gathered in accordance to the number of their resistance as well as industrial standard of water. Coliform contamination, and stool coliform were determined.

Results : During the study period, 340 samples were gathered, of which 261 (76.8%) had MPN of zero whereas 79 (32.2%) and 39 (11.5%) had MPN of greater than zero and 3, respectively. Totally, 27 samples have shown contamination of coliform type. Contamination was revealed to be maximum in the third and minimum in the 11^th month of sampling (16 samples vs. zero sample). Among districts, Lethar and Moallem Square have shown the highest and the least percentage of contamination (60% vs. 17.1%).

Conclusion : We have found still a great gap between the quality of drinking water in Kashan as compared to the standard measures. Since providing drinking water with the highest quality is of utmost importance in the society health, further attentions should be paid to the monitoring systems and also the sources of contamination.