This rulemaking is mandated under the America's Water Infrastructure Act (AWIA), which became law on October 23, 2018. The AWIA, section 2010(a), mandates the EPA promulgate, within 2 years of the date of enactment, a regulation that authorizes State primary enforcement authorities (primacy agencies) to require an assessment of restructuring options for a public water system (PWS) that frequently violates health-based standards and is unwilling or unable to take feasible corrective actions to return to compliance or that has unsuccessfully attempted feasible and affordable actions to return to compliance. The mandatory assessment must be tailored to the water system's size, type, and other factors and cannot be overly burdensome on the assessed system. The regulation also must describe the methods by which the primacy agency may offer liability protection to a "non-responsible" PWS, which, based on a completed, primacy-agency-approved consolidation assessment and consolidation plan, undertakes physical, administrative, or managerial consolidation with an assessed public water system. The AWIA, section 2009(a), also revises the definition of a consolidation plan under the Safe Drinking Water Act (SDWA), subsection 1414(h)(1), to include a contract for significant managerial or administrative functions of a public water system (PWS).