Contamination of groundwater systems in the US and Canada by enteric pathogens, 1990-2013: a review and pooled-analysis.

Background: Up to 150 million North Americans currently use a groundwater system as their principal drinking water source. These systems are a potential source of exposure to enteric pathogens, contributing to the burden of waterborne disease. Waterborne disease outbreaks have been associated with US and Canadian groundwater systems over the past two decades.