Editing Drinking-water toxic contaminant concentration (section)

== Boundary Conditions ==
Boundary inclusions encompass all toxic chemical contaminants present in drinking water at the point of use, with a focus on nitrate as a representative contaminant. This includes contamination from agricultural runoff, industrial effluents, and natural geochemical sources. Boundary exclusions involve contaminants not present at the point of use, such as those confined to source waters without reaching consumer taps, as well as non-toxic substances or parameters unrelated to chemical contamination, such as microbial pathogens or physical water quality characteristics.