THE USE OF RAINWATER AS A RELIABLE ALTERNATIVE FOR DRINKING PURPOSE IN DRY ZONES IN SRI LANKA: A COMPARATIVE STUDY IN THE MEDAWACHCHIYA AND KEBITHIGOLLEWA AREA, ANURADHAPURA

Abstract

Access to safe drinking water remains a critical public health issue in the dry zone of Sri Lanka, particularly the North Central Province (NCP), where the prevalence of chronic kidney disease of unknown aetiology (CKDu) is high. This study investigates the safety and suitability of rainwater as an alternative drinking water source by comparing its quality with six commonly used water sources: well water (WLW), tube well water (TWW), tap water (TPW), tank water (TNW), reverse osmosis water (ROW), rainwater (RNW), and spring water (SPW) in Medawachchiya (MED) and Kebithigollewa (KEB) divisions. In this study, 53 families from the MED division and 72 families from the KEB division were randomly selected. A total of 213 water samples commonly consumed by these families were collected in triplicate from their respective lsources. The collected water samples were analyzed in for key chemical parameters, including pH, conductivity, total hardness, and alkalinity and were evaluated against the drinking water standards introduced by the World Health Organization (WHO) and Sri Lankan Standards Institution (SLSI). According to the results, the pH values of all the water samples were within the acceptable limits (6.5 8.5). The conductivity of the different water sources in both areas was increasing in the order of ROW (32.9±1.85 μS/cm) < RNW (33.7±16.3 μS/cm) < TNW (268.55±1.55 μS/cm) < TPW (559±128 μS/cm) < TWW (765±80 μS/cm) < WLW (860±526 μS/cm). The total hardness of most of the water sources in both regions fell within the acceptable range (250 – 600 ppm), while some WLW and TWW samples in both regions recorded higher values (>700 ppm). The alkalinity of TPW, WLW, and TNW demonstrated extreme values (>850 ppm) in both regions. RNW and ROW exhibited significantly lower conductivities (<50 μS/cm) while RNW showed lower hardness (<12 ppm) and alkalinity (<128.0 ppm) than ROW in both regions. The results highlight that there was no significant difference (Mann-Whitney test, p>0.05) between the ROW and RNW in terms of the water quality parameters tested. Therefore, rainwater can be promoted as a reliable source of drinking water in the dry zone of Sri Lanka following verification of its microbiological safety.