Technical Memorandum Report No. 83
Bacterial Contamination of Water Resources on Moen, Truk Islands, Federated States of Micronesia
by F. DeWolfe Miller, Philip S. Moravcik, Nascha Siren, & Sanphy William
September 1991
ABSTRACT
Shallow wells and individual rainwater catchment systems meet the water requirements of many Micronesians. The quality of this water is a matter of public health interest because this region suffers from a high incidence of gastrointestinal disorders and water-related diseases. Poor sanitary conditions and particularly inappropriate excreta disposal practices pose a significant threat to shallow groundwater quality. Groundwater is usually used for nondrinking purposes; however, when alternative water sources are unavailable groundwater may be consumed. Rainwater catchment systems are the preferred source of drinking water. Catchment systems are often poorly maintained and storage capacity inadequate to last through even brief dry periods. The relationship between ambient sanitary conditions and shallow groundwater quality was examined on the island of Moen, Truk, Federated States of Micronesia. The relationship between construction parameters and maintenance of rainwater catchment systems and the quality of water contained in the storage tanks was also examined. At 13 sites, samples of groundwater were obtained either from specially constructed test-holes or from selected wells that met certain construction criteria. Sanitary conditions in the areas surrounding each site were evaluated. Special attention was paid to the proximity of latrines and to the presence of animals and standing water. Samples taken from these test holes and wells were analyzed for fecal coliform. Thirty-two rainwater catchment systems were examined for parameters of construction and maintenance. Samples from each tank were analyzed for total and fecal coliform bacteria. All determinations were made according to the membrane filtration method as described in the Standard Methods for the Examination of Water and Wastewater, 16th ed. Generally, sanitary conditions were observed to be extremely poor. Groundwater in all of the test holes and wells was contaminated with fecal coliform (range = 16 to 360,000 colony forming units/100 ml). No correlation between any of the examined parameters of sanitation and the degree of contamination was established. Rainwater-catchment tank water was of superior quality compared to the groundwater (average total coliform = 110, average fecal coliform = 14 colony forming units/100 ml). The most important determinant of tank water quality was whether or not water from the island’s central distribution system was put into the tank.