as a title of my post there is toxic rivers in africa which can kill human being ,the water of the rivers are toxic and high levels of E.coli in the rivers also Cheetah Bridge, a river in Alexandra, has E.coli levels of 2.4 million per 100 ml,and they advice the people who live around that place no to drink that water not good for human to drink that much toxic water 
reason behind why e.coli levels is too high in africa rivers and the reason is not good sanitation system and human waste dispose system and that waste mix in water and human can handle low amount of ecoli