The Environmental Protection Agency has finalized regulations to require water systems to replace millions of lead pipes with safer alternatives for carrying drinking water into U.S. homes. Before replacing them, water systems must identify where these lead service lines are located due to incomplete inventories. We conducted a randomized controlled trial to evaluate an intervention that targeted properties with unknown pipe material in Trenton, New Jersey—a community with older housing stock and a high concentration of people of color, renters, and households experiencing poverty. The intervention included two treatments: door hangers with information about a self-inspection process that allowed residents to submit a photo of their service line, and similar door hangers offering gift card incentives upon submission of a self-inspection. These treatments had null or small effects on residents' participation in self-inspection. Under 1% of treated addresses participated in a self-inspection, including those offered the highest incentive of $100.