Abstract
The quality of drinking water is an extremely important factor in public health. The main sources of drinking water in the Kingdom of Saudi Arabia (KSA) are bottled water, purified groundwater, and desalinated seawater. This study aimed to assess drinking water quality and evaluate the performance of water purification plants in Al-Hassa and with the aid of the water quality index (WQI). A total of 150 water samples were collected from 30 water purification plants. The physiochemical characteristics of drinking water, including the pH, TDS, EC, turbidity, free chlorine, total hardness, anions (Cl, HCO3, SO4, NO3, and F), cations (Na, K, Ca, and Mg), iron, and manganese, were investigated. The results revealed that the purified water was of acceptable quality for drinking with respect to the measured physiochemical characteristics. The overall water purification efficiency for the reduction in total dissolved salts and related anions and cations was over 90%. For instance, the average TDS values in groundwater were 1916 +/- 806 mg/L, which decreased to 118 +/- 32.9 mg/L in purified water. The WQI results showed that all the collected purified water samples were considered to be of excellent quality (class I) for drinking. Meanwhile, 81.7% of the untreated groundwater samples were considered to be poor quality (class III), and 11.7% were considered to be very poor quality (class IV) due to their high contents of dissolved salts. The purification of the groundwater improved its quality from very poor/poor quality (classes III and IV) to excellent water quality (class I). A Piper diagram revealed that 80% of the investigated groundwater samples were of the sodium chloride-sulfate water type. Overall, we found that the groundwater in the investigated area is not suitable for drinking purposes unless further purification techniques are applied.