water stream over rocks


Microbial communities and sources of bacteria in Honolulu’s water supply

Microbial communities and sources of bacteria in Honolulu’s water supply

National Institute for Water Resources, Water Resources Research Institute Program


The overarching goal of the project is to characterize microbial communities and sources of microbes in Honolulu’s water supply. This is the first in-depth analysis of microbes in our water supply which combines cultivation-based and molecular approaches and sets the following objectives: 1) characterization of our source water and drinking water microbiome, 2) identification of wells which are under direct surface water influence, and 3) risk identification; we will determine whether the source of microbial indicators in compromised groundwater wells or the water distribution system is from soil or human sewage. The project is expected to last for two years, with the first year focusing on analyses of water samples collected from source waters (spring and tunnel water) and from the distribution system at sites selected by the Board of Water Supply (BWS). At the end of the first year we will evaluate the approach (i.e. ultrafiltration vs. grab sample) and select study areas (hot spots) for more focused and intensive sampling. Priority will be given to sites that address the most urgent needs of the BWS (e.g. Navy’s fuel spill site in Aiea). Water samples will be analyzed for heterotorphic plate count, total coliforms, E. coli, enterococci, C. perfringens, F+ specific coliphages by cultivation-based techniques, while concentrations of sewage specific markers (human-associated Bacteroides and human polyomaviruses) will be determined by qPCR. Microbial community composition will be determined using high-throughput sequencing. Although this project is focused on Oahu, the problems faced and targeted by this proposal are applicable to the wider region of the Pacific and beyond.

The project will enhance assessment of water resources and related management decisions in Hawaii, which will increase the reliability of our water supply. The project will establish baseline data to evaluate long-term changes in our water supply (e.g. climate change related, slow leakage of contaminants, salinization, etc.) and increase disaster readiness as impact and recovery of the drinking water system can be studied when the water supply has been compromised (e.g. sewage, biological, or other contamination). The project will also enhance water resource management and improve our understanding of sources and dynamics of microbial contaminants in our drinking water supply. The project will strengthen the partnership between WRRC and the Honolulu BWS.