What is the highest level of a contaminant allowed in drinking water?

• A. Treatment Techniques (TT)
• B. Maximum Contaminant Levels (MCLs)
• C. Action Levels (AL)
• D. Water Quality Standards (WQS)

Answer: (B)

Understanding regulatory limits for drinking water contaminants is the key. Maximum Contaminant Levels are the enforceable limits that tell utilities the highest concentration of a contaminant allowed in drinking water. They’re established under the Safe Drinking Water Act by the EPA and require monitoring and treatment to keep levels at or below that ceiling, protecting public health.

Other terms describe different approaches. Treatment Techniques are alternative compliance methods used when a contaminant’s exact measurement isn’t feasible or practical; they aren’t a single universal maximum. Action Levels set triggers for additional action for specific contaminants (like lead or copper) based on samples, but they don’t define the overall maximum permitted in all drinking water. Water Quality Standards is a broader category that includes various criteria, not the specific highest permissible value for all contaminants.

So the highest level of a contaminant allowed in drinking water is defined by the Maximum Contaminant Levels.