Why are there two values listed for the U.S. EPA secondary standard for Aluminum in drinking water?
The U.S. EPA Secondary Drinking Standard for Aluminum is listed as “0.05 to 0.2 mg/L,” or 50 to 200 ppb. The alleged basis for this secondary or “nuisance” standard is that it causes color and scale or sedimentation. For the full guidance, see: http://www.epa.gov/safewater/consumer/2n… For all the other standards, however, only one number is given. Of course pH has two numbers to describe the range (6.5 to 8.5), but I can’t imagine that this is the case for Aluminum. So which is the standard — 0.05 or 0.2??? Does anyone know why there are two numbers?
