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Climate Change is a Threat to Health: Declining Water Quality, Increasing Waterborne Disease

As climate change worsens, changing precipitation patterns and rising water temperatures often bring negative impacts to human health and life.

Many areas, both in the United States and globally, experience more intense precipitation as a result of climate change. Much of this falls as heavy rainstorms. Flooding often follows such storms and can jeopardize water quality.

In rural areas, runoff picks up animal wastes, pesticides, and fertilizers. 

In cities, floodwaters not only carry toxins and other contaminants but can also overwhelm sewage systems, causing untreated sewage to flow directly into waterways.

Contamination of drinking water by bacteria, viruses, and protozoa can trigger outbreaks of waterborne disease like the diarrheal diseases legionella, campylobacteriosis, and cholera.  Warmer water temperatures also promote the growth and reproduction of these diseases.

For more on climate change's impact on water quality and waterborne disease, download PSR's Fact Sheet: Climate Change Contaminates Your Water (PDF)

Other areas experience decreased precipitation and seasonal or persistent droughts. Drought conditions not only reduce water supply; they also impair water quality because as water supplies decline, the concentration of contaminants increases.

Additionally, lack of access to clean water prevents adequate hydration, disrupts good hygiene, and hinders the production of agriculture and livestock. 

Even the vast waters of the ocean are affected by climate change. Rising carbon dioxide emissions are causing ocean temperatures to warm and to become more acidic.

The combination of higher surface water and increased nutrient loading from agricultural runoff contribute to harmful algae blooms that produce biotoxins. Consumption of fish or shellfish contaminated with toxins can cause neurological damage, respiratory impairment, skin irritations, and diarrhea. 

Increases in ocean acidity threaten coral reefs and the future of shellfish like oysters, clams, and mussels. Where people depend heavily on seafood for food and income, economic status and nutrition are both likely to suffer.