States that regulate supplemental disinfection of domestic water systems typically do NOT require reporting of which test results per the Safe Drinking Water Act?

The correct answer is centered on the fact that the Safe Drinking Water Act (SDWA) does not mandate the reporting of Legionella test results for domestic water systems. While Legionella is a significant concern related to waterborne diseases, especially in relation to recreational water and building water systems, it does not fall under the same regulatory requirements as contaminants like lead, nitrates, or coliform bacteria.

Lead, nitrates, and coliform are contaminants that are closely monitored and regulated due to their known health risks. The SDWA requires water systems to regularly test for these substances and report results to ensure public safety. On the other hand, Legionella testing is generally not part of these mandatory reporting requirements, primarily because it serves more as a secondary measure to compliment existing disinfection methods rather than a baseline requirement for safe drinking water.

Thus, while recommendations and guidelines around Legionella management do exist for plumbing systems, they are not enforced under the same legislative framework as the other contaminants listed, leading to the conclusion that supplemental disinfection reporting of Legionella test results is not required under the SDWA.