A significant proportion of the water supply in the U.S. Virgin Islands canes from the rainfall which is stored in cisterns. Since cistern water is not part of the public distribution system, it is not covered by the Safe Drinking Water Act (Public Law 93-523). The objective of this study was to determine whether cistern water supplies pose a potential health hazard to their users.
The cistern water supplies were studied to assess the types of heterotrophic bacteria, algae, and protozoa that may be present. The bacterial study was directed towards identifying those organisms capable of causing disease in water supplies. Total coliform, fecal streptococcus and Salmonella sp. were enumerated. The presence of coliform bacteria, fecal streptococcus and Salmonella sp. in most of the cistern water supplies suggested a potential health problem.
Algae and protozoa were found in several cistern waters, which indicated a high level of microbial diversity. These complex ecosystems suggested a continuous input of carbon and energy sources into the cisterns. The pollution of these cistern water supplies seemed to be of extreme significance, which has been overlooked by those involved in ascertaining the microbial quality of all drinking water in the U.S. Virgin Islands.