1. Human Health We all drink water that comes from a source: this may be a lake or local river. In countries that have poor screening and purification practices, people often get water-borne disease outbreaks such as cholera and tuberculosis. Every year, there are an estimated 3–5 million cholera cases and 100,000–120,000 deaths due to cholera. (WHO estimates that only 5–10% of cases are officially reported.)