The blue liquid inside of a portable restroom toilet area is composed of a variety chemicals which may include a fragrance and deodorizing agents that neutralize the smells that human waste can generate. Traditionally, anti-bacterial agents such as formaldehyde were added to kill bacteria within the tank however the modern approach favors the addition of enzymes and biocides instead. The enzymes speed up the decomposition process while the biocides consume the bacteria that produces odors. In addition to these chemicals, a third ingredient, blue dye, is added to the liquid to act as an indicator that turns green when mixed with urine. It also helps mask the contents of the tank from anyone who steps inside.
