Percentages of outbreak deficiencies in public water systems associated with untreated and improperly treated source water by year, 1971 to 2006, excluding outbreaks associated with Legionella and treatment deficiencies in mixed water sources. Percentages of outbreak deficiencies in public water systems associated with untreated and improperly treated source water by year, 1971 to 2006, excluding outbreaks associated with Legionella and treatment deficiencies in mixed water sources. SDWA, Safe Drinking Water Act; SWTR, Surface Water Treatment Rule. Gunther F. Craun et al. Clin. Microbiol. Rev. 2010; doi:10.1128/CMR.00077-09