Water Justice Act This bill addresses affordable access to clean water by establishing, expanding, or extending various programs or requirements related to drinking water infrastructure, water pollution control, water supply, water recycling, water efficiency, or conservation programs. Specifically, the bill provides $50 billion in FY2020 supplemental appropriations to the Environmental Protection Agency (EPA) for programs that reduce contaminants of concern in drinking water, such as grant programs for lead testing or remediation efforts in schools, child care programs, or high-risk communities. The funds are designated as an emergency requirement, which exempts the funds from discretionary spending limits and other budget enforcement rules. Each year, the EPA must obligate specified amounts of funding for several water infrastructure programs, including state revolving fund programs and grant programs for managing or controlling water pollution. The EPA must also establish a grant program to help communities that serve environmentally at-risk households and low-income households afford the costs for remediating contaminated drinking water. Further, the Department of Health and Human Services may make grants to states to assist low-income households in meeting their needs for drinking water, wastewater, and stormwater services. In addition, the EPA must promulgate an interim national primary drinking water regulation for perfluoroalkyl or polyfluoroalkyl substances, commonly referred to as PFAS, which may have adverse human health effects. Finally, the bill establishes or reauthorizes a variety of programs that provide financial support for water supply projects, water recycling or reuse projects, rural water systems, water efficiency improvements, or conservation programs.