Final answer:
To inquire about the safety of community tap water, Mario should contact the Environmental Protection Agency (EPA), which sets and enforces water quality standards under the Safe Drinking Water Act.
Step-by-step explanation:
Mario should contact the Environmental Protection Agency (EPA) to learn more about the safety of his community's tap water. The EPA is the United States government agency responsible for ensuring that public drinking water is safe by setting standards and regulations under the Safe Drinking Water Act. The EPA oversees states, local governments, and water suppliers to enforce these standards and protect public health. The agency also monitors contaminants and oversees the implementation of various programs to prevent and control pollution in water resources.