Water resource management requires simple tools to enable managers to make decisions. This is the case for water quality indices that provide access to clear, synthetic and well-targeted information. In this study, we have chosen two indices based on two different approaches, the Microbiological Quality Index (MQI), which is determined from bacteriological analyses of water, and the Water Quality Index (WQI), which is based on physicochemical parameters. The Water Quality Index (WQI) shows a longitudinal upstream-downstream variation and ranges from is between five (5) (Null Faecal Contamination) at sampling point P1 and 3.4 (Moderate Fecal Contamination) at P2. The Water Quality Index (WQI) ranges from a low of 14.08 (excellent water quality) at the P1 level to a high of 93.05 at the P2 level (poor water quality) receiving wastewater discharges. The WQI results for P3 and P4, show that the water is of good quality (downstream of P2), which shows the degree of self-purification of the Oum Er Rabia River, regardless of the sampling period. Finally, the results of the MQI corroborate those obtained with the WQI for the water quality of the different sampling points.

Water is one of the most crucial substances for life. In order to maintain their public health, each and every country has defined standards of drinking water quality, beyond which the water is considered harmful for human health. The current study compares physical, chemical, and biological standards of drinking water quality for the USA, EU, Japan, India, and Bangladesh, considering 4 physical parameters (namely, color, odor, taste, and turbidity), 35 chemical parameters (such as Calcium (Ca), Magnesium (Mg), Phosphate (PO43-), Sodium (Na), Phenolic compounds, Nitrite (NO2-), Arsenic (As), Aluminum (Al), etc.) and 2 biological parameters (i.e., Coliform (Fecal) and Coliform (Total)). The data has been collected from several secondary sources and since processes of data collection for water quality differ from one another, this aspect has been ignored. No variation has been found in biological water quality standards along with physical quality standards of the considered regions. In order to find out the differences in chemical parameters, standard ANOVA and pair-wise F-test have been conducted. There was no disparity among chemical parameters in ANOVA test. Moreover, thanks to the few excessive values of the standards (as in case of Bangladesh), the COD value is 4 mg/L, whereas in other countries this parameter is much less. However, the chemical parameters of water quality standards in Bangladesh vary significantly from other countries. Besides, there has been no variation among the standards of other countries, even though they are located in different continents. Most interestingly, despite being neighbors, Bangladesh and India differ significantly in this regard.