RESUMEN
Water is the basis of life and health. The health of food and water supply plays an important role in human health. One of the methods of water desalination is membrane filter reverse osmosis method. This method is used for desalination of drinking water supply in Qom. This is a descriptive, cross-sectional study designed to determine the quality of treated water in Qom desalination plant in year 2002. Inlet and outlet water samples of this plant were examined by the standard examination methods and the collected data were compared with national and international standards. Excel software was used for statistical analysis. The results showed that the residual chlorine concentration, total hardness and fluoride concentration were lower than the minimum standard limit set for drinking water. The pH was also lower than the minimum standard limit. Microbial contamination was detected in 6% of samples. The results show that the acidity of water was lower than standard in whole plant. This gives corrosive properties to the water and increases the dissolution of materials, which are in contact with this water. In order to eliminate the secondary contamination, the concentration of residual chlorine should be 1 mg/l. But, none of the measurements showed a concentration as high as this value. As fluoride is an important element for health and growth of bone and teeth, especially in growing children, fluoride should be added to the drinking water. As the relationship between hardness of water and cardiovascular diseases has been established, it can be concluded that this drinking water supply can increase the risk of cardiovascular diseases in long time. Dilution of this water is recommended to adjust various factors to the standard limits and keep the total dissolved solids low