Seasonal household variation in harvested rainwater availability in Siaya County, Kenya: a modelling analysis

Abstract Rainwater harvesting reliability, the proportion of days annually when rainwater demand is fully met, is challenging to estimate from cross-sectional household surveys that underpin international monitoring. This study aims to develop and evaluate a rainwater harvesting reliability model that integrates household surveys with gridded precipitation data. We interviewed 234 households in rural Siaya County, Kenya in two survey campaigns, administering a standard questionnaire that also identified the source of household stored drinking-water. Logistic mixed effects models estimated stored rainwater availability from household and climatological variables, with random effects accounting for unobserved heterogeneity. Household rainwater availability was significantly associated with seasonality, storage capacity, and access to alternative improved water sources. Most households (96.9%) that consumed rainwater faced insufficient supply of rainwater available for potable needs throughout the year, with intermittencies during the short rains for most households with alternative improved sources. Although not significant, stored rainwater lasts longer for households whose only improved water source was rainwater (299.6 ± 50.7 days) compared to those having multiple improved sources (136.3 ± 81.3 days). Such modelling analysis could enable rainwater harvesting reliability estimation, and thereby targeted follow-up fieldwork to support rainwater harvesting.