Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 67-70).This thesis accomplishes three tasks. First, it verifies the EC-Kit under different water source conditions by comparing it to a laboratory standard method, the IDEXX Quanti-Tray[tm]. The EC-Kit is a simple, inexpensive field test kit that contains complementary tests for Escherichia coli and total coliform: the Colilert[tm] 10-milliliter presence/absence test and 3MTMS Petrifilm[tm] test. This work was executed by analyzing 521 water samples collected in Capiz Province, Philippines as well as 40 water samples from the Charles River in Cambridge, Massachusetts. Second, it determines the risk level for drinking water sources according to E.coli and total coliform levels in Capiz Province for difference locations and source types. Third, this study contributes to an ongoing mapping project, aimed at creating an interactive, searchable map of water quality results from EC-Kit and Quanti-Tray[tm]. The results of the study reveal that each component of EC-Kit and the entire kit itself is correlated to Quanti-Tray[tm] in a statistically significant way. Moreover, from the calculations of error and proportional reduction in error for unimproved/improved water sources, it is possible to make better predictions with just the use of the Colilert[tm] test, but not just the use of the TM T Petrifilm . This is because the detection limits for PetrifilmTM are an order of magnitude higher than Colilert[tm], namely PetrifilmTM colony counts of 1-10/1 mL sample results fall within the High and colony counts of 10-100/1 mL of sample fall within the Very High risk level categories, whereas positive Colilert[tm] results fall within the Intermediate, High, and Very High risk level categories. Most importantly, the EC-Kit allows for the best reduction in error, with a proportional reduction in error of 63% for unimproved water sources and 60% for improved water sources. This finding is significant because it means that a simple, inexpensive field kit can change our understanding of the safety of drinking water compared to simply knowing the United Nations infrastructure designation of improved versus unimproved water sources. Furthermore, the statistical analysis revealed that while the EC-Kit does not exactly match the Quanti-Tray[tm] results, it still provides useful information for assessing at-risk water sources.by Patty Chuang.M.Eng
