Number of outbreaks associated with drinking water by system type and month (n = 762), 1971 to 2006, excluding outbreaks associated with commercially bottled water (n = 11), bulk water purchase (n = 1), mixed water systems (n = 3), and unknown water systems (n = 3). Number of outbreaks associated with drinking water by system type and month (n = 762), 1971 to 2006, excluding outbreaks associated with commercially bottled water (n = 11), bulk water purchase (n = 1), mixed water systems (n = 3), and unknown water systems (n = 3). Gunther F. Craun et al. Clin. Microbiol. Rev. 2010; doi:10.1128/CMR.00077-09