Which rule most directly guards against the presence of Escherichia coli in the water supply?

The Total Coliform Rule is specifically designed to ensure safe drinking water by monitoring and controlling the presence of coliform bacteria, which include Escherichia coli (E. coli). This rule requires water systems to regularly test their water for coliform contamination, and a positive test for E. coli is taken very seriously. If E. coli is detected, it indicates potential contamination with fecal matter and presents a serious health risk, prompting immediate and effective action to protect public health.

In contrast, while the Safe Drinking Water Act framework ensures the overall safety of drinking water, its broader scope covers various contaminants and drinking water standards rather than specifically targeting E. coli. The Lead and Copper Rule focuses on controlling lead and copper levels in drinking water, addressing different health risks. The Disinfection Byproducts Rule deals with chemical byproducts resulting from water disinfection processes but does not directly relate to bacterial contamination. Thus, the Total Coliform Rule is the most pertinent regulation when it comes to guarding against E. coli in the water supply.