Background: The use of overhung latrines, habits of rearing fishes by human excreta, houses on stilts, aquaculture, living in boats, transportation; recently, farm fishing grows quickly, especially people raising fish in floating rafts uses tiny pieces of fish meat to breed fish and the left over of this food is thrown directly to the river; besides, popular use of pesticides in agriculture can affect directly to water quality of Tien and Hau rivers that the local inhabitants collect to use for drinking and everyday activities in Dong Thap, Vinh Long and Can Tho provinces.