evidence: Colombo district, Sri Lanka. Twenty-six brands of drinking water were collected from the Colombo district (19 locations) microbial quality was detected by checking the total coliforms (TC), fecal coliforms (FC), heterotrophic bacteria, fungi and algae. The results revealed that 50 % of drinking water brands violated the [...] Considering the urbanization rates in Sri Lanka, Colombo is one of the most highly urbanized cities. More than 10 % of the population of Sri Lanka lives in the Colombo district. Eighty percent of the water demand in Colombo is fulfilled by the Kelani River and it is a primary source of drinking water (Liyanage and Yamada, 2017). According to the Food Control Administration Unit of the Ministry of Health (2019), twenty-six brands of bottled water are available in the Colombo district markets. The bottled water manufacturers in Sri Lanka mostly use dug wells, tube wells, and springs as a water source for bottling and most bottled water contains purified underground water (Piyarathna et al., 2020). Some of those bottled water manufacturers use underground water from the Kelani [...] that may have adverse effects on human health, and each company that prepares drinking water has to follow the stipulated standards (WHO, 2011). The Ministry of Health and SLSI have stipulated the standards for drinking water in Sri Lanka.