The standards of surface waters of the world depend on the Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD) contents of the waters and turbidity level. The pollution level of surface waters and the chemical contents within the waters could also be another standard. Could you please check the water quality index (WQI) on google?
Surface waters, though, are often high in turbidity. The most important microbiological measure of drinking-water quality is a group of bacteria called coliforms. Ngoc Nguyen