On the demand side, several studies have stressed the importance of income (Immurana et al., 2022); education and information (Alexander et al., 2019), Adil et al. (2021); Legge et al. (2021); Pakhtigian et al. (2022), resource constraints, as well as socio-cultural environment (Munamati et al., 2016) as important determinants of the access to, and use of, sanitation infrastructure and services. The argument is that information and education shift household preferences towards sanitation use while increasing income and relaxing resource constraints, generally, make sanitation services affordable to households. These studies have been conducted mostly at the aggregate level and do not establish causality. Other researchers stress the importance of accountability and advocacy as important factors in access and use of sanitation services. Some studies also highlight the critical role of information and peer effects in overcoming social and cultural barriers in the use of sanitation (Adil et al., 2021; Alexander et al., 2019; Legge et al., 2021; Pakhtigian et al., 2022, among others) Researchers interested in the supply of infrastructure services have focused on the characteristics of sanitation infrastructure and services, political institutions and the environment in which services are provided as well as political accountability and advocacy generated through voice and accountability. Ashraf et al. (2016) and Batley and Mcloughlin (2015) argue that sanitation infrastructure and services are characterized by indivisibility as well as externalities; hence, have to be provided by the public sector else the quantity provided will be sub-optimal. In low income countries, private provision may not even be feasible because of affordability. Other researchers have focused on the type of political institutions that provide sanitation services more effectively. Deacon (2009) argue that democracies provide better public services, including sanitation, to citizens relative to autocracies, probably because of increased accountability. Similarly, Keefer and Khemani (2005); Khemani (2015) argue that political incentives emanating from visibility and political pressure determines which public goods will be provided in a society.<sup>7</sup> Looking at sanitation issues through an institutional lens, data from 85 countries are analyzed by Anbarci et al. (2009) to show that corruption negatively affects both efforts to improve drinking water and sanitation. Breen and Gillanders (2022) using data on 45,000 households’ across Africa provide strong evidence that local corruption in the utilities sector impedes everyone’s access to clean water and sanitation. Similarly, some researchers argue that the supply of sanitation is influenced by the institutional environment (Francois et al., 2021; Hepworth et al., 2022; Hout et al., 2022).

An aspect of the provision of public services generally, and sanitation in particular, is _visibility_ and accountability. The more visible a project is and the more policy makers are held accountable for its provision, the greater the quantity of such services that will be provided; the reverse is also true—policy makers tend to provide less of services that are not visible and for which they are not held accountable. _Voice_ shines a spotlight on sanitation thus making it _visible_ as well as helping to keep policy makers _accountable_ for its provision. Adil et al. (2021) finds that information and increased accountability improves access to safe drinking water and sanitation in Punjab, Pakistan. Similarly, Hout et al. (2022) finds that increased accountability increases both access and sustainability of sanitation in Kenya.

A large amount of research focuses on testing the effects of foreign aid in providing access to sanitation (Abell ́an and Alonso, 2022; Gopalan and Rajan, 2016; Ndikumana and Pickbourn, 2017; Pickbourn et al., 2022, among others) and generally finds a significant and positive effect of aid on access to sanitation. These studies are generally conducted at the aggregate level using a variety of estimation methods. These researchers argue that international aid affects the demand for sanitation by changing the marginal utility of sanitation through health education and other information 7An interesting case is provided by Narzetti and Marques (2021), who seem to suggest that in vulnerable areas in Brazil, sanitation issues have a very low degree of visibility in the eyes of regulators than they do elsewhere. One way to see it is that governmental entities resign from their roles there, as evidenced by the lack of inclusion and application of regulation and public policies in vulnerable areas.

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