Water Utility Safety Checklist

In the 1960s, the National Aeronautics and Space Administration, along with the Pillsbury Corporation, designed a quality control program to protect astronauts from food poisoning on the first manned space missions. The Hazard Analysis and Critical Control Point system (HACCP) differed from previous models because it tested not only the finished food product but also the raw ingredients used throughout the manufacturing process. Subsequently, HACCP guidelines were adopted, expanded and refined by the World Health Organization for international application in water purification as well as food production. The philosophy behind this "multiple barrier" approach is that it is cheaper and safer to prevent contaminants from getting into drinking water than to try to remove or neutralize them after they have.

Protection of Source Water

• In areas with multiple sources (such as a lake, river and underground stream), the one with the highest-quality water is preferable because fewer contaminants at point of origin will reduce reliance on treatment. Whether new or established, all sources should be analyzed to determine what conditions may lead to increased risk of contamination (for example, storms, animal manure, seasonal growth of microorganisms) and appropriate steps taken to protect the water before it enters the utility plant.

Coagulation, Flocculation and Sedimentation

• These terms refer to the tendency of small foreign particles in the water to bind together and form larger, heavier particles. The degree to which these contaminants are naturally eliminated by sinking down and settling at the bottom of the source must be incorporated into the design of an effective filtration system.

Filtration

• Mesh is the first line of defense against large waterborne contaminants but after that, two main categories of filtration are used at North American water treatment utilities. Granulated activated carbon filtration is the most expensive but also the most effective at screening out both biological and chemical contaminants. Traditional sand filtration traps large molecules but might not catch the smaller molecules of toxins, including some pesticides and herbicides. Advance knowledge of the environmental pollutants most likely to endanger the water supply is essential to implementing an effective filtration system.

Disinfection

• Adding chlorine to drinking water kills off potentially lethal microbes causing a wide range of diseases, including cholera, typhoid and dysentery. Even though chlorinated drinking water has been linked to increased risk for some kinds of cancer, too little chlorine can be even more dangerous if it fails to neutralize common waterborne pathogens such as E. coli and cryptosporidium. Since chlorine breaks down quickly, concentrations in tap water may vary, so scrupulous monitoring by utilities is essential to protecting, rather than endangering, public health.

Protection of Distribution System

• Incompetence of management and staff and inadequate or nonexistent monitoring at water utilities have been identified as contributing factors in some outbreaks of waterborne disease, including the Walkerton tragedy in Ontario, Canada, in 2000, when 2,300 people contracted E. coli from drinking water and seven died. HACCP mandates constant vigilance to ensure that the water coming out of faucets is safe to drink.