A study by the aquatic research institute Eawag highlights which elements of safe drinking water service are vital in reducing diarrhoeal diseases among children in low- and middle-income countries. Using safe drinking water services means that the water is obtained from a source that is managed and meets the criteria defined under the SDGs for “Safely Managed Drinking Water” (SMDW). “The risk of diarrhoeal disease falls significantly when all SDG criteria of safely managed drinking water services are met,” explains Esther Greenwood, researcher at Eawag’s Department of Sanitation, Water and Solid Waste for Development.

The data analysed by Esther Greenwood and Tim Julian, researcher at Eawag’s Department of Environmental Microbiology, together with an international team, stems from household surveys conducted by UNICEF and includes information from 26,796 households in Africa, Asia and the Americas. 27% of all children lived in a household with drinking water supply that met all SMDW criteria. According to the United Nations, water is considered safely managed if taken from a water source which by design protects from outside contamination, is accessible on-site (at home) and is free from contamination by faecal matter and chemicals. Furthermore, the water must be available when needed – whether from a water source directly on site or in the form of sufficient water supplies.

Various factors contribute to illness

If any of these criteria are not met, the risk of diarrhoeal diseases in children can rise sharply – for several reasons, as the researchers found. “The most influential factor was whether sufficient quantities of water are available when needed,” says Greenwood. If, for example, water is only available at certain times of the day or only seasonally, the risk of illness increases. “We assume that availability means people can, for example, wash their hands more frequently,” explains the researcher. In general, the availability of water in the home significantly improves hygiene conditions. The location where water is consumed also has a clear influence. Contamination levels of E. coli are substantially higher in stored drinking water at home than directly at drinking water sources, such as communal taps or wells. This suggests that transport containers or the storage of water may contribute to higher levels of contamination.

Data as a decision aid

This study is the first multi-country assessment of the impacts of safe water, as defined by the SDGs, on child diarrhoeal disease. Previous assessments, which highlighted the role of water quality in diarrhoeal disease, focused on less comprehensive definitions of safe water, or were only conducted in a single region or country. The link between diarrhoeal diseases and contaminated water is therefore not, in principle, a groundbreaking discovery. Nonetheless, many countries do not yet meet the criteria for the SDG-defined quality standards for a safely managed source of drinking water. This usually requires significant investments, and data is essential to justify them. “We were able to demonstrate that the use of a higher standard of drinking water service has an effect on health,” says Esther Greenwood. “The data now available can help decision-makers prioritise potential measures or investments.” For the study shows that access to water alone is a good start, but by no means sufficient. From a health perspective, it is essential not only to provide access to a supply of drinking water, but also to ensure that it meets the criteria for “Safely Managed Drinking Water” (SMDW): Free from faecal contamination, easy accessibility and availability with sufficient supplies. Moreover, improvements in collection practices and storage are necessary.