Can Municipal Water Regulations Prevent Cross-Contamination?

Food and beverage manufacturers and processors in the U.S. operate on the premise that incoming municipal water is safe, and they will always receive notice of any anomaly in time to protect their processes and products in case of contamination.

EPA drinking water regulations are cited as the rationale to give municipal water users a safe-harbor-like exemption to bypass water in their written food safety plans and not to evaluate their water integrity risks in a formal, analytical, or scientific way that facilitates planning, prevention, and risk mitigation.

At the same time, final Food Safety Modernization Act, or FSMA, rules make the food and beverage manufacturers responsible for ensuring that the water they use does not contaminate their product. But how sure can they really be that their incoming water is safe enough to mitigate the need for additional water safety precautions?

Not Structured for Food Safety

The U.S. EPA rules that implement the Safe Drinking Water Act use a level of protection based on water consumption data for a household of four, the viability and virulence of the organisms of concern, and the effective dose considering stomach acid as an effective barrier and developed immunity based on repeated exposure to the same water source.

Image Credit: Atlantium Technologies
UV system on the incoming water supply protects a food plant in the U.S. against microbial contamination.

However, food manufacturing facilities don’t have “stomach acid.” A food manufacturing or packing plant “drinks” almost 90 percent of the water it takes, so its risk profile is significantly different than that of an individual. Most of the water a plant “drinks”—90 percent compared to the 5 percent for the individual—is used for product, or used for cleaning, cooling, making ice, or various processing tasks like pushing product through pipes. These uses give microbes an opportunity to find a niche and grow and thrive, in essence contaminating or infecting the facility. Sometimes the municipal water is used to wash the outside of closures, containers for distribution, and cases—and this municipal water can transmit microbes through the food supply system. The 2010 Oregon dairy Salmonella outbreak illustrated this risk.

The EPA drinking water risk assessment yields rules for both prevention (treatment techniques) and performance assessment.

EPA preventive rules require water suppliers to meet the treatment standards (regardless of technique) for at least 95 percent of the water they distribute to the public. This provides about 5 percent flexibility from an operational standpoint (calculated by time or by volume). A system that does not achieve the 95 percent standard would have a treatment technique violation and would have to notify the public either in their annual Consumer Confidence Report or more immediately, depending on the circumstances.

Of course, no consumer—even if their flow rate is 500,000 gallons a day—would necessarily know if they were getting some of the allowable 5 percent off-spec water.

The theory is that 5 percent off-spec water would be dispersed enough that no individual intake would get enough to create serious contamination or illness. So a household is unlikely to be endangered by the small amount of off-spec water it would receive in the 300 gallons it would use during a day. But a food manufacturing facility could be significantly impacted based on its much higher consumption of 10,000 to 500,000 gallons a day. In food safety terms, this 5 percent threshold would be the equivalent of allowing 5 of every 100 gallons produced at a milk plant to be at risk of not having been treated adequately to inactivate the pathogens inside, clearly not an appropriate food safety standard.