The improvement of sanitation conditions in slums (1) is difficult in part because of economic and institutional environments that often prevent private or public investment in infrastructure. This analysis of sanitation conditions in informal settlements in Nairobi and Kampala compares user practices. It also identifies the main actors involved in the provision of overlapping sanitation systems, involving a multitude of small-scale providers, along with the challenges these present. The paper goes on to describe a new market-based approach in Nairobi, developed by a social enterprise, Sanergy, which is responsible for the construction of facilities and the collection and treatment of wastes. The system improves user satisfaction, community wellbeing and environmental quality, pointing to a clear opportunity for such market-based interventions where a customer base already pays for sub-standard services. There remain challenges, however, around the ability to scale up and finance these providers, especially in complex operating environments that increase transactional costs for companies.KEywOrds bottom of the pyramid / East Africa / informal settlements / sanitation / social enterprise I. IntrOductIOnDiarrhoea kills more children per year than the combination of other communicable diseases including HIV/AIDS, malaria and measles. Nearly 9 out of 10 diarrhoea cases are linked to inadequate water, sanitation and hygiene, which contribute to more than two million deaths annually. (2) This is a particularly serious problem in urban informal settlements, where high population density can lead to the build-up of large volumes of waste and the quick transmission of communicable diseases such as diarrhoea and cholera. (3) This same high density makes the provision of adequate water and sanitation particularly problematic in these settlements.High density is not the only problem, however. It is difficult to provide improved sanitation, defined as a facility that "hygienically separates human excreta from human contact", (4) in informal settlements for a number of interconnected reasons. (5) These include the lack of highlevel political leadership aimed at improving living standards and access to basic services; (6) weak or conflicting governance arrangements that Mark O'Keefe is interested in the development of aspirational products and innovative services within emerging markets. His research focuses on the improving access and availability of basic water, sanitation and hygiene (wAsH) services within urban informal settlements. He works in the Environmental social sciences (Ess) department at Eawag.

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The toilets used most in informal urban settlements have detrimental consequences for the environment and human health due to the lack of proper collection and treatment of toilet waste. Concepts for safe, sustainable and affordable sanitation systems exist, but their feasibility and acceptance have to be investigated at an early stage of development, which is difficult due to the high costs of building working models. In this paper, we present an approach to estimate acceptance in a valid and representative form with only one working model, and apply it to test an innovative zero-emission toilet with recycling of wash water. Four basic principles were specified for investigation and nine hypotheses formulated to test the feasibility and acceptance of these principles: source separation of urine and feces with subsequent collection for resource recovery; provision of wash water in a separate cycle with on-site recovery through a membrane bioreactor; a convenient and attractive overall design; and a financially sustainable business plan. In Kampala (Uganda), in 2013, data was collected from 22 regular users, 308 one-time users and a representative sample of 1538 participants. Qualitative data was collected from the users, who evaluated their likes, perceived benefits, social norms and expected ease of use based on verbal and visual information. Most of the hypotheses were confirmed, indicating the feasibility and acceptance of the basic principles. Source separation and on-site water recovery were found to be feasible and accepted, provided users can be convinced that the emptying service and water recovery process work reliably. In the survey, the toilet was evaluated favorably and 51% of the participants agreed to be placed on a bogus waiting list. However, some design challenges were revealed, such as the size of the toilet, hiding feces from view and improving the separation of urine and water.

Approximately 2.8 billion people rely on polluting cooking fuels (e.g. wood, kerosene), exposing them to health-damaging household air pollution. A key access barrier to clean cooking fuels (e.g. liquefied petroleum gas (LPG)) is affordability. By enabling households to pay in small increments, pay-as-you-go (PAYG) LPG could help promote clean cooking, and support continued LPG use through periods of economic downturn. We investigate the ability of PAYG LPG to sustain access to clean cooking from January 2018-June 2020, including during COVID-19 lockdown (March-June 2020) in an informal settlement in Nairobi, Kenya. We utilize novel PAYG LPG smart meter data to document cooking/spending patterns from 426 PAYG LPG customers and semi-structured interviews among a subset of seven households. Objective cooking pattern comparisons are made to those cooking with full 6kg cylinder LPG and polluting fuel users from 23 households in peri-urban Eldoret in western Kenya, using stove monitoring data. Customers’ average PAYG LPG consumption was 0.97 kg/capita/month (11.6 kg/capita/year) prior to COVID-19 lockdown. Despite adverse economic impacts of the lockdown, 95% of households continued using PAYG LPG, and consumption increased to 1.22 kg/capita/month (March-June 2020). Daily cooking events using PAYG LPG increased by 60% (1.07 events/day (pre-lockdown) to 1.72 events/day (lockdown)). In contrast, among seven households purchasing full 6kg cylinder LPG in Eldoret, average days/month using LPG declined by 75% (17 to four days) during COVID-19 lockdown. Median PAYG LPG payment frequency doubled (from every 8 days to every 4 days) during lockdown, while average payment amount was nearly halved (336 Kenyan Shillings (KSh)/US$3.08 to 179 KSh/US$1.64).Interviewed customers reported numerous benefits of PAYG LPG beyond fuel affordability, including safety, time savings, cylinder delivery and user-friendliness. PAYG LPG helped sustain clean cooking during COVID-19 lockdown, possibly averting increases in polluting cooking fuel use and associated household air pollution exposures.Graphical AbstractHighlightsFirst study to report long-term cooking/spending patterns using PAYG LPG smart meter data95% of 301 active PAYG LPG customers in February 2020 continued to use the fuel during COVID-19 lockdownDaily cooking events using PAYG LPG increased by 60% during COVID-19 lockdownMedian payment frequency increased 50%, while single payment amount decreased 50% during lockdownThree-quarters of PAYG LPG households in this study were first time LPG users

The inadequate provision of sanitation in informal urban settlements, also known as slums, continues to be an important issue. New technologies and services are being designed to solve this problem. However, the history of failed sanitation programmes and projects highlights a lack of understanding of how slum inhabitants decide on investing in such products and services. In this paper, we gather perspectives from potential clients and investigate how slum inhabitants (1) perceive the current situation and whether they desire improvements of sanitation, (2) how they evaluate a new toilet that is still in development, and how (3) social processes and (4) constraints affect decisions. Data were collected through interviewing 1538 people within a general household survey. People using shared and public latrines desire an improvement of their sanitation facilities. The lack of water for washing is perceived by residents as a the biggest problem when accessing current latrines. The new toilet was mostly evaluated positively: people like it, expect large health benefits from it and it complies with cultural norms. However, people also expect some problems with the functioning of the toilet and expect opposition to pay for the service, due to the high costs and a lack of space to set up new toilets.