The Efficacy of a Low-technology, Low-cost Water Filter in Removing Pathogens and Preventing Disease during Long-term Household Use
Katherine Westphal Powerpoint Slides
Introduction: Worldwide 1.1 billion people lack access to improved drinking water. Inaccessibility to improved drinking water and a lack of adequate sanitation and hygiene result in more than 1.8 million deaths annually from diarrhea; the majority of these deaths occur among children under the age of five. Point-of-use water treatment systems have been shown to be an effective method for reducing the burden of diarrheal diseases. The Potters for Peace ceramic water filter (CWF) is one such point-of-use water treatment system promoted to reduce the burden of water-borne diseases. The CWF is a low-technology, low-cost water treatment system that utilizes filtration and colloidal silver, which acts as a disinfectant, to purify water.
Methods: A joint effort between the Johns Hopkins Center for Water and Health and the Center for Refugee and Disaster Response examined the effectiveness of the CWFs in removing water-borne pathogens in three phases. In the first phase of the research, CWFs from Honduras were tested for bacterial and viral removal in the laboratory at the Johns Hopkins Bloomberg School of Public Health. The second phase of the research consisted of a cross-sectional survey of households in Nicaragua. Information gathered from this survey was used to evaluate the use and sustainability of the CWF. In the third phase, CWFs currently being used were tested in-situ for bacterial removal.
Results (to date): The CWF removes between 3.22 and 6.06 logs of spiked bacteria in the laboratory although its ability to remove viruses is minimal. Bacterial removal by non-silver impregnated filters is significantly less than those impregnated with silver. In Nicaragua, 48.5% of households surveyed who received a CWF over the past four years no longer used the CWF daily, largely due to a broken spigot or filter element. Of the filters currently in use, the CWF successfully removed 100% of E. coli from 53% (23/43 CWF) and greater than 95% of E. coli from 78% (34/43 CWF) of the households sampled that had E. coli present in their source water.
Discussion: Although there is no doubt that the CWF improves the quality of water, it does not consistently remove waterborne pathogens to meet standards set by the United States Environmental Protection Agency. However, the WHO considers it important to take into consideration the economic, environmental and social constraints of a country before defining appropriate water quality standards. The drop-off in usage of the CWF, which is largely associated with a broken spigot, suggests that the CWP design needs to be modified for long-term use. Point-of-use water treatment is an accessible technology in environments where public utilities are either unreliable or do not exist. If used appropriately, point-of-use water treatment can effectively reduce the burden of diarrheal disease.
Katherine Westphal is originally from Minnesota and is a graduate of Bucknell University with a degree in chemical engineering. Katherine served as a Peace Corps volunteer in Panama where she designed and constructed water systems for rural villages. Most recently she worked in Uganda as a Project Manager for an initiative to promote sustainable employment for local communities. Katherine is currently earning her Master of Public Health at the Johns Hopkins Bloomberg School of Public Health where she serves as the Vice President for the J.B. Grant International Health Society.
