Development of new integrated water quality index (IWQI) model to evaluate the drinking suitability of water

Several water quality indices are used to evaluate water suitability for potable use; however, every index has strengths and weaknesses which limits the applicability and ease of use. There is a need to develop a universally accepted water quality index (WQI) which is flexible enough to represent drinking water suitability all over world. A new water quality index has been developed. The concentration of any parameter below desirable limit as well as above permissible limit will contribute to the overall increase in the index value; therefore the index is called as Integrated Water Quality Index (IWQI). In traditional WQI, desirable or permissible limits are evaluated as the standard allowable limit but in the IWQI we consider both the limits are considered, avoiding the confusion around the adoption of standard values. Based on this concept, IWQI has been classified into 5 categories viz. excellent (< 1), good (1-2), marginal (2-3), poor (3-5) and unsuitable (> 5); depends on the concentration of cations (Ca, Mg, Na and K), anions (Cl, SO4 and NO3) and other parameters (pH, TDS) present in groundwater samples. The result reveals that 2% samples excellent for drinking, 39% good, 43% marginal, 8% poor and 8% unsuitable for drinking. The results are obtained at 20% deficit of its maximum permissible limit and can be adjusted per user need to alert water managers of possible human health concerns with drinking water. The water quality is mainly affected due to the industrial and agricultural inputs into the aquifer system. The North West region is influenced by anthropogenic inputs from industrial effluents, whereas the South West region is affected from agricultural runoff due to a high level of agricultural activity. The IWQI is flexible, unbiased, easy to calculate and time saving, and will provide useful information to prioritize and maintain the water quality of potable sources and reduce human health impacts from using poor-quality groundwater resources.