The impact of low cost sanitation on groundwater contamination in the city of Addis Ababa

Abstract

Providing clean water remains a challenge in many African countries. Ethiopia, with the second largest population in Africa is also faced with this predicament. Efforts to improve supply have focused on abstracting groundwater. Although relatively cheaper to utilize, groundwater is prone to contamination, from improperly disposed of waste, particularly urban areas with no appropriate sanitation services. The city of Addis Ababa is faced with this difficult situation. Currently about 75 % of the population of Addis Ababa has access to sanitation in the form of pit latrines, while 0.6 % has access to sewerage services. The rest of the population is considered to have no access. This proliferation of pit latrines in the city has enhanced the risk of groundwater contamination. This research was initiated with the objective of assessing the temporal and spatial extent of contamination of groundwater due to human waste. It attempted to review the quality of water in deep wells and springs. The data analyzed indicates that the temporal and spatial extent of contamination has increased over the past few decades. Over abstraction of groundwater has also been observed. Whilst contaminant levels such as nitrates and chlorides in many wells are below maximum permissible values, few wells in the centre of the city have exhibited higher values. This steady temporal increase may soon make some wells unsuitable for human consumption. Efforts to reduce this risk will need to focus on sewerage services provision, review of existing environmental policy, public awareness drive and sustainable groundwater management.