Can Cross-Connection Be Hazardous?
Yes, in the old days many disease epidemics were caused by cross-connections between potable water systems and raw river water or lake water piping systems. Epidemics of typhoid and cholera were often caused by backflow occurrences from these sources and people died or were very ill. A few of the contaminants caused by cross-connections are:
  • Anti-freeze
  • Bacteria cultures from laboratories
  • Boiler water with chemicals
  • Blood and body fluids from funeral homes
  • Chemicals
  • Dyes
  • Freon
  • Heavy metals (such as arsenic)
  • Pesticides, herbicides, and fungicides
  • Petrochemicals
  • Propane gas
  • Sewage
  • Untreated river, sea, or lake water
  • Water from carwashes
  • Water from flush toilets
  • Worms
  • Worm treatment for poultry

This is only a partial list of documented cases of potable water contamination by virtue of cross-connections and backflow occurrences. These cases still happen everyday.