Could climate change lead to more pathogens in drinking water? A feature article by Ensia, published at the University of Minnesota’s Institute on the Environment, explains how heavy rainfall and high temperatures could increase the risk of drinking water contamination by microbes.
The risk affects particularly groundwater sources in areas where the geology and farming operations make them susceptible to contamination, as rainwater picks up pathogens from manure used as fertiliser, and then seeps into aquifers. Human faecal pathogens from septic systems can also be carried by rainwater into the groundwater.
The risk of contamination by pathogens is highest in the case of private wells, as households that rely on them are usually not required to test or treat the water. In the United States, more than 13 million households get their drinking water from wells.
Drought can also increase the risk of pathogen contamination: pathogens can become more concentrated as less water remains in aquifers, thus people whose drinking water comes from that source could ingest a higher dose of pathogens and become ill.
Contaminated well water has been reported in rural areas of Wisconsin and Appalachia. Municipal water systems that use groundwater could be at risk as well, since groundwater does not need to be disinfected before it is distributed.
The measures to reduce risks include controls on manure storage and use, to prevent contamination, and groundwater monitoring and disinfection by municipalities and individuals.
While the risk of drinking water contamination by pathogens is another reason to address climate change, expert in waterborne diseases Karen Levy from the University of Washington, warns it is important to trust public drinking water systems, which should be protected, rather than turning to alternatives such as bottled water.