Under the Lead and Copper Rule, what percentage of tested water services must be below 0.015 Mg/l Lead (Pb)?

The Lead and Copper Rule is a critical regulation aimed at protecting public health by minimizing lead and copper levels in drinking water. According to the rule, utilities are required to comply with certain action levels to ensure that the water supplied to consumers is not harmful.

In the context of lead levels specifically, the rule mandates that at least 90% of the tested water samples must be below 0.015 mg/L (milligrams per liter) of lead. This threshold is established because it correlates with protective measures to reduce the risk of lead exposure, particularly for vulnerable populations such as children and pregnant women.

Achieving this standard signifies that the majority of consumer water sources are safe from elevated lead levels, thus supporting public health objectives. Utilities that do not meet this requirement may be required to take further actions, such as corrosion control treatment or public education initiatives, to address lead contamination in their water supply.

Therefore, the requirement that 90% of tested samples be below 0.015 mg/L reflects a strong commitment to ensuring safe drinking water and public health, which is why the correct answer is 90%.