Red Hill Health Impact Act This bill requires the Department of Health and Human Services (HHS) to establish a registry and conduct a study of those impacted by the Red Hill Incident of November 20, 2021, in which fuel from a storage facility contaminated the water system of Joint Base Pearl Harbor-Hickam in Hawaii. Specifically, HHS must establish a voluntary registry of those impacted by the incident to collect data on the health effects of the contamination. HHS must also conduct an epidemiological study for at least 20 years to assess the long-term health impacts of the incident, based on an associated feasibility assessment.