Urban Water Demand, Supply and Health Outcomes in Nairobi County, Kenya

Abstract

Introduction: This thesis provides evidence to inform strategies on provision and access of clean drinking water in Nairobi city through provision of data on multi-year patterns on water distribution, association with reported water borne illnesses, forecasting these patterns and disease associations over time and investigate what would be the effect of select mitigation strategies on water sufficiency and public health. Objectives: The objectives were: 1) To determine the spatio-temporal patterns of the distribution, consumption, and sufficiency of domestic piped water in Nairobi City; 2) To determine the association between water distribution patterns and sufficiency with incidence of cholera in Nairobi City; 3) To model the forecasted risk of water insufficiency levels in Nairobi City by 2025 and determine the optimal mitigation strategies for minimizing this risk. Materials and methods: To determine the spatio-temporal patterns of domestic water distribution, consumption and sufficiency, data on piped water distribution network, supply and the rationing programs was obtained from Nairobi City Water and Sewerage Company. Data on human population for Nairobi was obtained from WorldPop. To determine the association between water sufficiency and occurrence of waterborne diseases, data on all events of cholera reported in health facilities in Nairobi monthly was obtained from the Kenya Health Information System (KHIS). First, the geographical accessibility to the health facilities and to specified cadres of health professionals for residents in Nairobi City was estimated while accounting for traffic congestion, an important determinant of healthcare utilisation and access. Using cholera incidence data from the health facilities that were accessible to most of the population, spatial cluster analysis was completed to determine cholera hotspots in Nairobi and their association with water sufficiency. Using data on monthly per capita water consumption in residential areas, data on annual population growth rate and nonrevenue water for Nairobi City, time series models were used to forecast water demand and estimate the proportion of Nairobi residents that would be at risk of water insufficiency by 2025. Results: Water sufficiency differed by residential areas, age of neighbourhood and population per itinerary. Compared to residents of low-income areas, those in middleand high-income areas were four and six times more likely to receive the recommended 1500 litres per capita per month respectively. Analysis of the geographical accessibility to healthcare facilities showed that less than 90% of Nairobi’s 4.1 million population were within a 45-minute drive to health facility during peak traffic hours. This increased to >90% during off-peak hours. Compared to secondary healthcare, the data showed a relatively higher optimal ratio of 4.45 healthcare professionals per 1000 people in facilities offering primary and tertiary healthcare during peak and off-peak hours. Cholera hotpots were predominantly in areas receiving less than 1500 litres per person per month, and households located more than 30 meters from a piped sewerage network. Results on forecasting water sufficiency showed that by 2025, monthly water consumption would increase in the middle (47%), middle/low (38%) and high-income areas (21%) whereas a decrease (68%) would be observed in the low-income areas. Discussion & Recommendations: Findings from this research highlight the need for improved water governance to enhance equity in water supply and access in Nairobi, reduction in the risk of waterborne diseases, and the need for urgent planning and investments to minimize risk of water insufficiency with the growing size of urban population of Nairobi.