Country-level sanitation access is monitored globally by the Joint Monitoring Programme (JMP). However, recent reports on sanitation access in high-income countries indicate that the JMP data may underestimate the prevalence of unsafely managed sanitation in these settings. This study explains the surveys that collect household-level wastewater management data in the U.S. and analyzes the accuracy and reliability of these data sets. From 1940 to 1990, sewage disposal data were collected comprehensively through the U.S. Decennial Census. These data are currently collected through the American Housing Survey (AHS) which appears to greatly underestimate the usage of onsite wastewater treatment systems (OWTS). In addition to these surveys, we highlight current efforts to introduce a sewage disposal question to the American Community Survey (ACS), localized efforts to collect wastewater data, and the Point-in-Time count of people experiencing homelessness. Using estimates of OWTS usage in new housing, this study provides the first defensible national estimate of OWTS usage since 1990. We estimate that 25.03% of U.S. households use OWTS which exceeds the AHS estimate (15.7%) by over 12 million households. This study discusses the potential for better wastewater data collection to inform future wastewater policy and improve the quality of life for U.S. residents.

  • The Decennial U.S. Census collected sewage disposal data until 1990 with no recent representative data.

  • We estimate 32.2 million U.S. housing units (25.03%) use onsite wastewater treatment systems (OWTS) using data from the Decennial Census and new housing.

  • Accurate data are needed to inform allocation of federal funding, but current data under-represent residents without access to safely managed sanitation.

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