Plumbing and Cross-Connections
Where there is a connection of any sort between the potable water supply, which is safe to drink, and any other source of water, there is the potential for the other source of water, usually seriously contaminated with microorganisms or chemicals, to cause disease or injury to people if the contaminated water flows back into the potable water supply. This is called a cross-connection, which is illegal and very dangerous. The contaminant enters the potable water supply when the pressure of the polluted liquid exceeds the pressure of the potable water. This is usually called backsiphonage or back flow. These cross-connections usually exist because of errors made when individuals doing the plumbing inadvertently connect the wrong pipes or hoses to the potable water supply or a hose from an acceptable plumbing fixture is submerged in a body of fluid, causing a submerged inlet of potable water to occur.
Cross-connections have resulted in numerous serious health problems. Because of a crossconnection in a large southern city, human blood coming from a funeral home ended up in water fountains in a building. In another incident, a key water system was contaminated with sodium hydroxide which may have come from a chemical company disposing of it. When a water main broke it caused a pressure differential allowing for the back flow. Antifreeze and other chemicals such as paraquat, chlordane, heptachlor, and other herbicides and insecticides, have been found in the water supply because of reduced pressure problems. Salt water from ports and water from rivers have also entered the potable water supply because of cross-connections.
Cruise ships are extremely vulnerable to problems of cross-connections because of the large number of pipes, hoses, and potential for submerged inlets in a vast number of sinks. It would be a problem to train all of the crew members in avoiding these situations especially when there are so many different languages spoken. Also, the passengers could easily contribute to the problems of submerged inlets in their own cabins.