While considerable advances in water supply and sanitation have occurred in OECD countries, pathogens can still enter water supply systems due to resistance to disinfection (e.g. Giardia, Cryptosporidium, and enteric viruses), treatment system deficiencies (e.g. inadequate disinfection), periodic treatment failures, or distribution system contamination. Excessive rainfall and agriculture runoff was the cause of the contamination. In Europe, significant outbreaks of water-borne pathogenic organisms have occurred in Sweden (Widerstrom et al.,