New research has found that water treatment reduces the odds of child mortality (death before age five) by about 30%. The study suggests that water treatment is a highly cost-effective way of saving lives. It costs roughly Ksh 324,000 ($2,800) to save a child’s life through water treatment.

More than 2 billion people around the world still drink contaminated water, and 1.5 million people die each year from diarrhea, many of them young children. Due to a lack of evidence, however, water treatment is often excluded from lists of the most cost-effective child-survival interventions, making it a massively under-funded intervention for saving lives.

The analysis by economist and Nobel laureate Michael Kremer (University of Chicago), Professor of Medicine Stephen Luby (Stanford University), economist Ricardo Maertens (Harvard University), and economist Brandon Tan (Harvard University) suggests that water treatment reduces the odds of child mortality (death before age five) by about 30%.

“As a public health physician, I want to highlight the significance of a 30% reduction in child mortality”, said Luby. “Somewhere approximately between one in every three and one in every four deaths of children under five could be prevented by water treatment.”

This meta-analysis provides new information by combining data from 15 different randomized evaluations of water treatment interventions set in low- and middle-income countries, to evaluate the impact on under-five child mortality. Five of the studies included in the meta-analysis took place in Kenya.

“In low-income countries, only 28% of the population have access to safely managed drinking water services,” said Nobel Laureate Michael Kremer, who has worked on different projects in Kenya for over 20 years. “If you take the meta-analysis estimate of improved water quality on child mortality, it suggests that a program that targeted that population would save approximately half a million children under five years of age annually at a cost of 1.3 billion dollars per year.”

The studies in the meta-analysis include a total of 25,526 subjects and 509 deaths. The authors screened 1,485 studies, reaching a final sample of 15 high-quality studies examining water chlorination (12), water filtration (2), and spring protection interventions (1). Combining all collected evidence, the authors find that water treatment is a highly cost-effective way to save lives.

This value is well below common thresholds for cost-effectiveness. For example, the World Health Organization (WHO) describes an intervention as “highly cost-effective” if it costs less than the GDP per capita of the country in question per disability adjusted life years (DALY) averted. One DALY represents the loss of one extra year of healthy life. The WHO lists the most cost-effective interventions for reproductive, maternal, newborn, and child health with a cost per DALY of $10 – $100, including childhood vaccination, treatment for diarrhea using oral rehydration solution, and malaria treatment.

The authors’ cost-effectiveness estimates of around $36 per DALY averted would rank water treatment among the most cost-effective interventions on the list. Taking cost data from two water treatment interventions in Kenya and Malawi, the estimated number of DALYs averted per dollar is more than fifty times greater than the WHO’s cost threshold for “highly cost-effective” interventions.

“We know well of the need to address child health, to address inequities in child survival so all children will be able to reach their fifth birthday, irrespective of where they live,” said Dr. Patrick Amoth, Director General in the Kenyan Ministry of Health “The meta-analysis clearly shows that there’s a significant reduction in mortality if we’re able to provide safe water. This calls for a policy shift, so that we can promote that as a high impact intervention.”

At present, however, access to water treatment remains low, despite several effective delivery systems being available. Furthermore, demand for safe water will increase due to threats of climate change and aquifer depletion that threaten existing sources of clean water. This study provides rigorous evidence that water treatment is one of the most cost-effective ways to reduce child mortality.

The authors propose that agencies like the WHO should consider adding water treatment to their list of highly cost-effective interventions. For policymakers and stakeholders, water treatment offers a significant opportunity to reduce child mortality and improve lives.

“Previously, water treatment has often not been considered a top priority for health spending, meaning that one in four people globally still drink contaminated water,” Prof. Kremer added. “This meta-analysis suggests that water treatment is one of the most cost-effective tools we have for decreasing child mortality. Policymakers focused on children’s health should aim to make water-treatment universally available.”