National Opportunity for Lead Exposure Accountability and Deterrence Act of 2019 This bill requires the Environmental Protection Agency (EPA) to revise the national primary drinking water regulations for lead and copper. The rule must direct public water systems to meet certain reporting requirements; the EPA to develop a sampling protocol and develop instructions for compliance with the protocol; the EPA, or the state exercising primary enforcement responsibility, to require on-site investigations for determining the source of lead when the concentration of lead or copper contamination exceeds specified levels; public water systems to meet certain notification and reporting requirements when lead or copper concentration limits are exceeded; the systems to develop and publish an inventory of the material composition of the service lines at residential and nonresidential facilities; the systems to collect and publish information about the ownership of those service lines; and the systems, when replacing lead service lines, to entirely replace the lines instead of partially replacing them. The EPA must also revise the rule to lower the allowable level of lead in drinking water.