In areas of the world with no piped water, people rely on 'black market' water - sold by informal vendors who have no oversight - which can be high-priced and have dangerously poor quality. But when informal vendors establish their own unions, they adopt rules that self-regulate and provide improved water pricing, quality and delivery.

This is according to a team of researchers from Arizona State University and the Graduate Institute of International and Developmental Studies in Geneva. Their findings, due to appear in print in World Development in early 2016, have been pre-published online at ScienceDirect.

Lead author Amber Wutich, an ASU anthropologist, says, "Our research shows that there are ways to ensure people have safe and affordable water service, even when they are not able to connect to a piped water grid."

Her team used an institutional framework to analyze how the markets operate; how cooperation among water vendors helps or hinders fair water delivery; and the differences in how vendors and clients view fairness as applied to rules, quality, quantity, costs, distribution and service related to the water market.

The research involved long-term participant-observation in squatter settlements and interviews with water vendors and clients in Cochabamba, Bolivia, scene of a noted "water war" in 2000.

In evaluating interactional, procedural and distributive justice, the researchers acknowledge that 'black market' water poses many challenges but has the potential to bridge supply gaps in urban water systems. The solution has long been regarded as undesirable but is increasingly recognized as unlikely to change for many urban poor communities in Africa, Asia and Latin America.

The researchers discovered that some informal vendors - who supply most of the water used by the region's urban poor - organize themselves in vendors' unions to ensure the delivery of safe, affordable water. Unionized vendors are better at setting up reliable delivery schedules, ensuring fair prices, and monitoring water quality, when compared to non-unionized vendors.

The team also found that vendors and clients share a desire to see everyone, even the poor, achieve a "human right to water." But the researchers caution that vendors tend to focus on issues like ensuring fair pricing, while their customers are more concerned with problems such as unreliable delivery and discriminatory treatment.

Among the team's recommendations is a greater role for water unions and increased community oversight over, and engagement with, these unions.

"Water vendors are often painted as the villains in the urban poor's struggle to get water. Our work shows that they can be allies, and points to ways that these informal water markets can become more reliable and just for the people who depend on them for survival," explains Wutich, an associate professor in the ASU School of Human Evolution and Social Change.