Climate change may affect drinking water quality and quantity as a result of an increase in the frequency and intensity of storms, warmer air temperatures and drought.
Water resources are important to both society and ecosystems. We depend on a reliable, clean supply of drinking water to sustain our health. We also need water for agriculture, energy production, navigation, recreation and manufacturing. Many of these uses put pressure on water resources and are stresses that are likely to be exacerbated by climate change. In some areas, water shortages will be less of a problem than increases in runoff, flooding or sea level rise. These effects can reduce the quality of water and can damage the infrastructure that we use to transport and deliver water.
Heavy downpours can increase the amount of runoff into rivers and lakes, washing sediment, nutrients, pollutants, trash, animal waste and other materials into water supplies, making them unusable, unsafe or in need of water treatment. More frequent storms and floods may cause overflows from sewage systems and treatment plants into freshwater sources used for drinking water.
Overflows from sewage systems and treatment plants may lead to an increase in the prevalence of water-borne parasites, such as Cryptosporidium and Giardia. Health impacts from water-borne parasites can be severe.
Health impacts from climate change impacts on surface and groundwater drinking water sources may include gastrointestinal illness like diarrhea, effects on the body's nervous and respiratory systems, or liver and kidney damage.