There are several classes of water pollutants. These are bacteria, viruses, protozoa and parasitic worms that enter sewage systems and untreated waste. Water pollution can pose health dangers to humans who come into contact with it, either directly or indirectly. Contaminated Drinking Water. The risks of your health being negatively impacted by polluted drinking water in a developed country is small in comparison with developing countries. However, it is possible to become ill from contaminated water. When you are out hiking, you can acquire giardiasis that can lead to the presentation of acute symptoms like vomiting and intense nausea. This infection is caused by drinking water that has been fouled by animal wastes in untreated waterways. In anthropogenic environments like cities and towns, the potential toxins are far more numerous.