Water problems never end. Milwaukee was the site of the largest cryptosporidium outbreak in U.S. history. The old "Town of Lake" water tower (pic), known as the Howard Avenue Water Purification Plant, became contaminated on about March 23rd and was shut-down on April 8th. Over 100 died, mostly elderly and those with weakened immune systems.
In Israel, we do have Cryptosporidium in Lake Kineret and all surface water streams (the few ones we still have). The source is domestic sewage. However, no mass disease episodes were reported.