VARIATIONS OF CHEMICAL QUALITY FOR DRINKING WATER

A comprehensive investigation was conducted in order to evaluate the quality of the groundwater inZarand plain of Chatrood region which supplies drinking water of Zarand city. Zarand plain withlongitude of 55°, 46َ- 57°,7َ and latitude of 30°,20َ -31°,44َ is one of Iran’s plains located in sub-basin ofDaranjir desert. Groundwater of Zarand plain supplies drinking water of many cities and villages locatedin and near the plain. Samples were collected from 11 water wells used as drinking water sources inZarand plain "Chatrood region", at least once at the middle of each month. By means of the standardmethods, a number of parameters were analyzed for each sample for the period of 7 years from 1996 to2003. Tests included measuring pH, electrical conductivity, total dissolved solid, total hardness, calcium,magnesium, sodium, potassium, bicarbonate, sulfate, chloride, and nitrate ions. Data analysis was done byusing t and Z-Test. Results indicated that water quality of water wells during studied period did not showany undesireable change. The quality of each parameter in drinking water wells of Zarand plain waswithin permissible limit and did not exceed neither the Iran’s standards nor WHO guidelines. Meanwhile,the quality of raw water resources of the plain in the final year of experiment was within "good" potabilitylimit based on Schuller’s diagram; it means raw water resources still kept its quality. Although the qualityof Zarand plain water resources comply with Iran’s standards and WHO guidelines increasing trend ofwater consumption and consecutive droughts in the studied region as well as severe water shortage, askfor conservation, preservation and monitoring of water resources.