Every glass of water that comes out of a Colorado tap has, at some point, been through a deliberate kill step aimed at the bacteria, viruses, and parasites that would otherwise make people sick. That kill step is disinfection, and as a Class D operator you are the last line of defense standing between a treatment plant and a waterborne disease outbreak. This guide covers what you need on day one: why disinfection exists, the disinfectants you'll actually handle, the basic chemistry happening in the pipe, how to read a chlorine residual, and how to stay alive around chlorine gas.
Why Disinfection Matters
Before modern water treatment, cities that drew drinking water from rivers and shallow wells suffered repeated epidemics of cholera, typhoid fever, and dysentery — diseases caused by pathogens (disease-causing microorganisms) present in water contaminated by human or animal waste. Th