Final answer:
Water filtration is a key step in eliminating outbreaks of water-borne diseases like cholera.
Step-by-step explanation:
The filtration of water supplied to cities has been a crucial step in eliminating most outbreaks of water-borne diseases, including cholera. Cholera is a bacterial disease caused by Vibrio cholerae, which is transmitted primarily through contaminated drinking water. Modern sanitation practices, such as filtration and disinfection, effectively eliminate the threat of cholera outbreaks. For example, in 1866, New York City experienced a cholera outbreak that was later traced back to contaminated drinking water. Since then, the implementation of proper water filtration systems has significantly reduced the incidence of cholera in developed countries.