Information regarding domestic water consumption is vital, as the Kathmandu Valley will soon be implementing the Melamchi Water Supply Project; however, updated information on the current situation after the 2015 Gorkha Earthquake (GEQ) is still lacking. We investigated the dynamics of domestic water consumption pre- and post-GEQ. The piped water supply was short, and consumption varied widely across the Kathmandu Upatyaka Khanepani Limited (KUKL) branches and altitude. The reduction in piped, ground, and jar water consumption and the increase in tanker water consumption post-GEQ appeared to be due to the impact of the GEQ. However, the impact did not appear to be prominent on per capita water consumption, although it was reduced from 117 to 99 L post-GEQ. Piped, ground, and tanker water use were associated with an increase and jar water use was associated with a decrease in water consumption. Despite improvements in quantity, inequality in water consumption and inequity in affordability across wealth status was well established. This study suggests to KUKL the areas of priority where improvements to supply are required, and recommends an emphasis on resuming performance. Policy planners should consider the existing inequity in affordability, which is a major issue in the United Nations Sustainable Development Goals.

This paper discusses vulnerability of freshwater resources in large and medium Nepalese river basins to environmental change based on evaluation of water resource availability and variation, resource development and use, ecological health and management capacity; and compares the situation with selected sub-basins of the Ganges and the Mekong basins in Asia. Results suggest that water resources in the medium river basins are more vulnerable than in the large basins; and Nepalese basins, in general, are more vulnerable than other selected basins in the Asian region. The vulnerability in the Nepalese basins is more related to poor management capacity followed by resources variation and the least to development pressure. The poor management capacity is mainly related to low productivity of water use and the resources stress is related mainly to variation of the resource.

A dropping nitrification reactor was proposed as a low-cost and energy-saving option for the removal of NH₄⁺-N from contaminated groundwater. The objectives of this study were to investigate NH₄⁺-N removal performance and the nitrogen removal pathway and to characterize the microbial communities in the reactor. Polyolefin sponge cubes (10 mm × 10 mm × 10 mm) were connected diagonally in a nylon thread to produce 1 m long dropping nitrification units. Synthetic groundwater containing 50 mg L⁻¹ NH₄⁺-N was added from the top of the hanging units at a flow rate of 4.32 L day⁻¹ for 56 days. Nitrogen-oxidizing microorganisms in the reactor removed 50.8–68.7% of the NH₄⁺-N in the groundwater, which was aerated with atmospheric oxygen as it flowed downwards through the sponge units. Nitrogen transformation and the functional bacteria contributing to it were stratified in the sponge units. Nitrosomonadales-like AOB predominated and transformed NH₄⁺-N to NO₂⁻-N in the upper part of the reactor. Nitrospirales-like NOB predominated and transformed NO₂⁻-N to NO₃⁻-N in the lower part of the reactor. The dropping nitrification reactor could be a promising technology for oxidizing NH₄⁺-N in groundwater and other similar contaminated wastewaters.

Kathmandu Valley faces water scarcity from decades of the added burden of water storage and treatment, which imposed cost. We estimated the method-specific cost of in-house drinking water treatment (9 L/day used) based on equipment price and life, daily operation time, fuel used, and consumables replacement frequency, which were Nepalese Rupees (NRs) 23, 57, 392, 586 and 799 for chemicals, ceramic filter, boiling, Euro-Guard and reverse osmosis-ultraviolet (RO-UV) water purification, respectively. The monthly average water treatment cost was estimated based on these estimates and treatment methods used in households, obtained from a questionnaire survey of 1500 households, and its socioeconomic relationship in a Nepalese urban context was investigated. Of the households, 75% practiced at least one treatment method, (average, 1.4). The estimated monthly average cost per household was NRs 380. The fixed effects model showed that the cost was significantly higher in Lalitpur district, and in high school education households. Higher water insecurity perception of respondents was the main determinant of higher treatment cost, which was especially true in Lalitpur district. Water treatment added extra financial burden, especially for the poor households which should be averted or minimized by concerned authorities to provide adequate quantity, quality, and access to drinking water for all.