This rulemaking is mandated under the America's Water Infrastructure Act (AWIA), which became law on October 23, 2018. The AWIA, section 2010(a), requires EPA to promulgate 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 should not be overly burdensome on the assessed system. The regulation also must include provisions regarding liability protection to a "non-responsible" PWS, which, based on a completed, primacy-agency-approved restructuring assessment and plan, consolidates with, or acquires ownership of an assessed PWS. The AWIA, section 2009(a), also revises the definition of a restructuring plan under the Safe Drinking Water Act (SDWA), subsection 1414(h)(1), to include a contract for significant managerial or administrative functions of a PWS.