Water Quality and Waterborne Disease

Many parts of the United States will experience more precipitation as a result of global warming and much of this increased rainfall likely will come during very heavy storms. Flooding following such storms could jeopardize water quality. In rural areas, runoff would pick up animal wastes, pesticides, and fertilizers as it traversed farms and fields. In cities, floodwaters carrying toxins and other contaminants could overwhelm sewage systems, causing untreated sewage to flow directly into waterways. The resulting contamination of drinking water by bacteria, viruses, and protozoa could trigger outbreaks of waterborne disease, while increased toxic contamination could have both acute and long-term health effects. Warmer water temperatures because of global warming would also threaten water quality by promoting the growth and reproduction of disease-causing bacteria in drinking water supplies.

In the ocean, the combination of higher surface water temperatures and increased nutrient loading from rivers carrying agricultural runoff, may contribute to harmful blooms of algal species that produce biotoxins. Consumption of fish or shellfish contaminated with these toxins can cause neurological damage, respiratory impairment, skin irritations, and diarrhea.

Some areas, both in the United Sates and globally, will experience decreased precipitation as a result of global warming. Drought conditions can also impair water quality because as water supplies decline the concentration of contaminants increases. Additionally, lack of access to clean water disrupts good hygiene and may prevent adequate hydration.

Download PSR's Fact Sheet:
The Medical and Public Health Impacts of Global Warming (PDF)