Tap Water Quality Degradation in an Intermittent Water Supply Area

Abstract Decentralized tap water systems are an important drinking source worldwide. A good quality, high-pressure continuous supply (CWS) is always the target of any urban settlement. However, in some areas reported with deteriorated quality even though treated well before supplying. Such deterioration widely from low availability and economically poor countries where supplied intermittently (IWS). This study focuses identifying IWS causes degradation using nitrate-nitrogen (NO 3 -N) as indicator stable isotopes hydrogen (δD) tracer. Nine reservoirs ninety municipal (ten per reservoir) samples were collected during wet (June–September) dry (November–February) seasons Kathmandu Valley (KV), Nepal. Ten percent exhibited higher NO -N than those their respective season, while 16% concentrations season. Similarly, isotopic signatures 3% 23% seasons, respectively. Coupling analysis between δD demonstrates close connection groundwater water. The results indicate intrusion primary component controlling variations within same distribution networks IWS. Meanwhile, obtained also probable KV usefulness a tool assessment systems.