Tap Water Quality Degradation in an Intermittent Water Supply Area

Shakya, Bijay Man, Nakamura, Takashi, Shrestha, Sadhana, Pathak, Sarad, Nishida, Kei and Malla, Rabin, (2022). Tap Water Quality Degradation in an Intermittent Water Supply Area. Water, Air, & Soil Pollution, 233 81-104

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  • Sub-type Journal article
    Author Shakya, Bijay Man
    Nakamura, Takashi
    Shrestha, Sadhana
    Pathak, Sarad
    Nishida, Kei
    Malla, Rabin
    Title Tap Water Quality Degradation in an Intermittent Water Supply Area
    Appearing in Water, Air, & Soil Pollution
    Volume 233
    Publication Date 2022-02-25
    Place of Publication New York
    Publisher Springer Link
    Start page 81
    End page 104
    Language eng
    Abstract Decentralized tap water systems are an important drinking water source worldwide. A good quality, high-pressure continuous water supply (CWS) is always the target of any urban settlement. However, tap water in some areas are reported with deteriorated water quality even though treated well before supplying. Such deterioration of tap water quality is reported widely from areas with low water availability and in economically poor countries where water are supplied intermittently (IWS). This study focuses in identifying tap water quality in IWS and causes of water quality degradation using nitrate-nitrogen (NO3-N) as an indicator and stable isotopes of hydrogen (δD) as tracer. Nine water reservoirs and ninety municipal tap water (ten per reservoir) samples were collected during the wet (June–September) and dry (November–February) seasons in the Kathmandu Valley (KV), Nepal. Ten percent of the tap water samples exhibited higher NO3-N than those of their respective reservoirs during the wet season, while 16% exhibited higher concentrations during the dry season. Similarly, the isotopic signatures of tap water exhibited 3% and 23% higher concentrations than those of their respective reservoirs during the wet and dry seasons, respectively. Coupling analysis between NO3-N and δD demonstrates close connection of groundwater and tap water. The results indicate groundwater intrusion as the primary component in controlling tap water quality variations within the same distribution networks during IWS. Meanwhile, the obtained results also indicate probable areas of intrusion in the KV as well as usefulness of δD as a tool in the assessment of tap water systems.
    Keyword Tap water contamination
    Intermittent water supply
    Low pressurized tap
    Groundwater intrusion
    Kathmandu Valley
    Copyright Holder The Authors
    Copyright Year 2022
    Copyright type Creative commons
    DOI https://doi.org/10.1007/s11270-021-05483-8
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    Created: Sat, 24 Sep 2022, 00:34:58 JST by Hanna Takemoto on behalf of UNU IAS