In drinking water, the more turbid it appears, the higher the chance that those using it could end up with gastrointestinal diseases. The water may be having contaminants such as viruses and pathogenic bacteria which are found attached to suspended solids. These solids may interfere with disinfection of the water.
Erosion and effluent from highly urbanized areas contribute to the turbidity of water in those areas. In open bodies of water, organisms such as phytoplankton can contribute to turbidity in the water.
A control group is needed to carry out the experiment, that control group is the one that is not injected with anything. Ethanol and pesticide need to be injected into separated groups to document whether it is one or the other that is harmful