The document discusses several waterborne diseases including cryptosporidiosis, giardiasis, legionnaires' disease, and pneumonia. It notes that while rare, waterborne disease outbreaks can still occur in the US if harmful elements contaminate water system pumps and pipes. This could lead to humans contracting diseases from drinking or being exposed to contaminated water, with possible symptoms ranging from diarrhea and stomach pains to death. The largest recorded outbreak was caused by cryptosporidium in Milwaukee in 1993, affecting over 400,000 people.