Drinking water contaminated by these organisms can cause diseases like cryptosporidium or giardia.
Symptoms can include nausea, diarrhea, weight loss, gas, and energy loss.
The quality of surface water is unpredictable, because the water continually moves and pollutants can be introduced at any time. In other words, an area of lake or stream that is fine one day may be contaminated the next. Biological contaminants can come from sewers and failed septic systems, boat toilets, animals, and other sources. Chemical contaminants, like gasoline, oil, pesticides, and heavy metals, can come from discharge pipes, chemical storage areas, gasoline tanks, oil drums, or anywhere chemicals have been used close to open water. To use surface water as a source for drinking water, you must have a properly constructed water intake and a treatment system that includes filtration and disinfection.