Taste as a Measure of Water Quality In Kathmandu Valley

Methods

Summary

Student volunteers from the Department of Environmental Sciences in Tribhuvan University in Kathmandu will collect duplicate water samples from a variety of public water sources in the Kathmandu Valley. At each water source, team members will interview users of the water source about why they use the water sources that they do, their opinions about the taste and quality of the water, and general questions about their family health; they will use an interview script. Student volunteers will analyze the water samples for bacteria (E. coli and total coliform). The duplicate samples will then be sent to a certified water laboratory for multiple metals analyses to be tested for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Interview responses will be analyzed to determine the factors that most influence water source choice and how important taste is for water source choice. Interview responses concerning health will be compared to water quality results to determine whether water contaminants in subjects' chosen sources are reflected in reported family health. In particular, the aspect of water taste will be evaluated to see whether it has any effect on public health, if and when taste is used for making decisions about water sources. Maps of groundwater contaminants will also be produced to inform local water planners of any patterns of contamination.

Challenges

Working conditions in Nepal are extremely difficult in the aftermath of the April, 2015 earthquake. Many roads are still blocked with debris and electricity is only available is only available in the city of Kathmandu for certain hours of the day. Because the water samples had to be analyzed for biological pathogens within 24 hours of collection, sample collection had to be carefully planned according to predicted availability of electricity. In addition, due to personal reasons, some of the subjects chose not answer all of the interview questions on the household questionnaires. Nevertheless, because we administered the questionnaires to multiple households at each sample site, we believe we have sufficient data for statistical analyses. Since we have chosen to have the samples analyzed for metals at a certified drinking water laboratory, the metals data will be of excellent quality. With the metals data we can make maps of the distribution of metals in the local aquifers; this in itself will be useful for local water planning.

Pre Analysis Plan

Factor analysis methods will be used to determine which factors affect water source choice for residents, whether taste is one of these factors, and how the factor of taste compares to other factors such as distance from home to the source or availability. We will also compare water analysis results to family health histories for each source to see whether there is an association between contaminants in the water and reported family health. In studying the health histories, we will consider possible confounding effects of tobacco/betel use and household socio-economic status (SES). We will compare taste judgments of the water sources to the water analysis results to see if there are any positive or negative associations with specific contaminants, such as e coli or manganese concentrations. We will also test for associations between taste judgments and family health histories (again, considering possible confounding factors such as tobacco use and SES). We will use ArcGIS to draw maps of water contaminants.