Abstract
In many low-income settings, non-state organizations compensate for limited state capacity by providing services that would otherwise be expected from the government. Such interventions can generate important welfare gains, but their consequences for the future provision of public services are theoretically ambiguous. When households gain access to a reliable decentralized technology, the marginal value of centralized provision may fall, reducing their willingness to support and finance collective infrastructure. Conversely, experiencing the benefits of reliable service delivery may raise households’ expectations, reveal the returns to improved provision, and increase demand for a collective solution.
The present study investigates the effect of randomized household access to a decentralized water-cleaning technology on willingness-to-pay for collective water provision as well as an incentivized contribution to a concrete communal water project. It thereby identifies whether personally experiencing a decentralized alternative changes revealed demand for collective provision. We investigate this question through a household-level randomized controlled trial in six villages in Uyui District, Tabora Region, Tanzania, where access to safe drinking water remains severely constrained. A total of 900 households are randomly assigned to one of three conditions: 360 households receive a household water-treatment device (Solvatten), provided free of charge by World Vision Tanzania, a humanitarian organization; 180 households receive an unconditional cash transfer designed to distinguish the effect of the water technology from the income or resource-transfer effect of receiving a valuable product; and 360 households form the control group. Two adult members of each household are interviewed separately at baseline and endline, yielding approximately 1,800 respondents and 3,600 person-wave observations.
The primary outcomes capture demand for a collective, village-level solution to unsafe drinking water. At baseline and endline, respondents complete a survey-based elicitation measuring their willingness to support an upgrade of a communal dug well at different household costs. At endline, respondents also make a real-stakes allocation from a monetary endowment, choosing how much to retain for themselves and how much to contribute toward upgrading a communal well with a hand pump and chlorination system. Contributions are matched by the project, providing an incentivized measure of households’ willingness to sacrifice private resources for collective water provision. Secondary outcomes capture the priority assigned to collective water provision and intended engagement in efforts to improve communal water infrastructure.
The household-level design identifies whether receiving a decentralized water technology changes the recipient’s own demand for collective provision. Interference may nevertheless arise if untreated households share the device or treated water or learn from the experiences of treated neighbors. We account for this possibility in four ways. First, the technology has limited capacity and is designed to serve a single household, restricting the scope for sharing. Second, households residing in a compound containing at least one treated household will be classified as compound-exposed. Third, spillovers beyond the compound will be estimated using spatial exposure mapping that captures each household’s distance-decay-weighted exposure to nearby treatment assignments, with own assignment entering separately. Conley spatial-HAC standard errors will additionally account for residual spatial correlation. Fourth, one village in which no treatment is distributed provides a treatment-free benchmark, useful for the models with repeated baseline and endline measures.
We relate primarily to two broad bodies of literature. First, our empirical approach builds on a large experimental literature studying the adoption, valuation, and welfare effects of water technologies (Ashraf et al. 2010; Kremer et al. 2011; Burlig et al. 2026). This literature provides the closest methodological and sectoral precedent for the present study but stops short of examining the downstream political consequences of decentralized water provision. Second, and more closely related conceptually, we add crucial experimental evidence to the literature on how non-state service provision affects the role of the state. One strand of this literature examines the supply side, demonstrating that NGO provision can alter government capacity and service production (Deserranno et al. 2025). Another strand examines the demand side, asking whether NGO and donor provision changes citizens’ preferences over service providers, perceptions of government legitimacy, and political engagement (Brass 2012; Dietrich and Winters 2015; Springman 2022). Existing approaches, however, have important limitations in identifying how experienced non-state provision affects demand for a public alternative. Brass (2012) relies on observational evidence, while Dietrich and Winters (2015) experimentally vary information about foreign funding. Springman (2022) examines the long-term effects of NGO health provision on preferences for NGO versus government service delivery through an ancillary evaluation of an earlier village-level RCT in Uganda.
In the present study, we combine the methodological rigor of the experimental water literature with the political-economy questions raised by research on non-state service provision. Rather than examine preferences over service providers and political engagement as the key outcomes, we treat them as potential mechanisms through which non-state provision may alter demand for a public alternative. We measure that demand directly through repeated willingness-to-pay elicitations and an incentivized, financially consequential contribution to a concrete communal water investment. The household-level design allows us to test with precision whether decentralized provision leads to private exit or strengthens collective voice.