Biosand filter reduces diarrheal disease in Dominican Republic villages

“This technology has the potential to bring safe drinking water to many people in developing countries around the world who don’t have access to it now,” said Mark Sobsey, Ph.D., professor of environmental sciences and engineering at UNC’s School of Public Health. “We can tremendously improve people’s health and quality of life if we can help them get a reliable source of clean drinking water. Our study shows that simple biosand filters actually do improve water quality and consequently improve the health of everyone in the home.”

Sobsey and researchers in UNC’s School of Public Health compared rates of diarrhea and the condition of drinking water in homes in two villages near Bonao, Dominican Republic. They monitored about 150 households without filters for four months, assessing the rate of illness. Then, about half the houses were given biosand filters – concrete containers that hold gravel and sand. All households were monitored for another six months. The team’s initial analysis showed the filter reduced diarrheal disease among household members by an estimated 30 percent to 40 percent, including in highly vulnerable young children less than 5 years old. At the end of the study, filters were given to all participating homes.

“These kinds of filters have been used in the developing world since the 1990s, but there was only anecdotal evidence that they actually improved health,” said Christine Stauber, a UNC doctoral candidate who helped direct the project in the Dominican Republic. “It was really exciting to collect scientific evidence in an objective study that showed the filters actually worked, at least in these communities.”

Preliminary results of the study were presented in February 2007 at the third annual Thirsting to Serve Water Conference in Grand Rapids, Mich.. More detailed findings will be presented and published later this year.

“This kind of field evidence provides the basis for encouraging more widespread promotion and use of these filters to reduce the global burden of diarrheal disease,” Sobsey said. “Diarrhea is one of the major causes of disease and death in developing countries.”

Dr. Gloria Ortiz, a UNC postdoctoral fellow, also helped direct the project in the Dominican Republic. She recently visited the villages and said residents told her that the filters make a great difference in their lives.

“They told me they no longer need to worry about sick children who have to miss school, or about taking the children to the doctor or finding money to buy medications to treat diarrhea,” she said. “Many told me that since they’ve been using the filters, no one in their house had gotten a single case of diarrhea. This is a tremendous step in improving their health and well-being.”

International Aid, a non-profit humanitarian healthcare agency, cited the UNC study while announcing a major safe water initiative that focuses on the distribution and use of a filter that uses the gravel and sand technology, but is housed in a plastic, rather than concrete container. The new filter weighs about 15 pounds, compared to about 300 pounds for the concrete filters.

“We didn’t use the lightweight filters in our research,” Sobsey said, “but we’re happy to know companies and agencies are embracing the proven technology of biosand filters and are looking for ways to improve and increase the usage. We know clean water not only improves, but saves lives.”