The impact of latrine contents and emptying practices on nitrogen contamination of well water in Kathmandu Valley, Nepal

Leaching of nitrogen-containing compounds (e.g., ammonia, nitrate) from pit latrines and seepage tanks into groundwater may pose health risks, given that groundwater is a significant source for drinking water in many low-income countries. In this study, three communities within Kathmandu, Nepal (Manohara, Kupondole, and Lokanthali) were visited to investigate the impact of pit latrines on groundwater quality, with a focus on understanding the fate of nitrogen-containing compounds specifically. Well water samples were analyzed over two seasons (wet and dry) for their nitrogen content, dissolved oxygen (DO), chemical oxidation demand (COD), and oxidation-reduction potential (ORP), and samples collected from within the nearby pits were also analyzed to determine nitrogen content and COD. Hand dug wells were found to be more likely receptors of contamination than tube wells, as expected, with inter-well variations related to the relative redox conditions in the wells. Increased pit-emptying frequency was related to lower levels of nitrogen in the latrines and in the nearest wells, suggesting this may be an effective strategy for reducing the risks of groundwater contamination in such settings, all else being equal