The ultimate purpose of control and prevention of backflow is to protect public health. Should a backflow condition occur, the “degree of hazard” must be understood in order to provide the proper backflow preventer to stop the hazard on hand. The degree of protection is determined based on the degree of hazard.
A low hazard application is when potential backflow can pollute the drinking water. Pollution is defined as materials that can cause undesirable effects to the water, such as discoloration, smell or taste, but will not cause sickness or death. A high hazard application is one where the potential backflow can contaminate the water supply. Contamination is defined as any impairment to the water quality such that contact with this water can result in illness or death.