What type of certification must liquid bleach used in public water systems have?

Liquid bleach used in public water systems must be NSF approved because NSF International is an organization that develops public health standards and certifications for food, water, and consumer goods. In the context of water treatment, NSF certification ensures that the bleach is safe for use in public water systems, meets specific safety and efficacy standards, and does not contain harmful contaminants that could compromise public health. On the other hand, while the EPA regulates water quality and safety standards, it does not specifically certify products used in water treatment, so it is not the correct answer in this context. The FDA is focused on food and drug safety, which does not apply to liquid bleach used in water systems. OSHA’s focus is on occupational health and safety, which also does not pertain directly to the certification of chemicals used in public water systems. Therefore, NSF approval is necessary for liquid bleach used in public water systems to ensure its suitability and safety for treating drinking water.