An Assessment of the Microbiological Water Quality of Sand Dams in Southeastern Kenya

Ruth Quinn,Sandy Cairncross,Manon Decker,Alison Parker,Orlando Avis

doi:10.3390/w10060708

Ruth Quinn, Sandy Cairncross + Show 3 more

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https://doi.org/10.3390/w10060708

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Abstract

Sand-storage dams have proven to be a successful water harvesting method and potential solution to water and food security issues in semi-arid regions such as south east Kenya. This paper examines the microbiological quality of water both contained in the sand dam via test holes and abstracted from it through covered wells and scoop holes. In total, the values of thermotolerant coliform (TTC) concentration, turbidity, and pH are presented for 47 covered wells, 36 scoop holes, and 29 test holes, as well as the conductivity values in conductivity in 39 covered wells and 11 scoop holes. The water from test holes and covered wells was microbiologically of better quality than the scoop holes with median TTC levels of 0/100 mL and 159/100 mL respectively. However, the median values of turbidity for both scoop holes (20–30 NTU) and covered wells (5–10 NTU) exceed the World Health Organisation (WHO) guideline values. In addition the conductivity of water from 23% of scoop holes and 26% of covered wells is above the recommended WHO limit. This study also found that sanitary surveys are not a useful indicator of water quality in sand dams; however, they can identify areas in which sanitation and improvement of water sources are needed.

Highlights

Two major expected impacts of climate change in semi-arid regions such as southeast Kenya are temperature rises and recurrent drought [1]
The turbidity tube only allows the identification of a range of Nephelometric Turbidity Unit (NTU) values so they should be treated as ordinal variables
The findings of this research indicate that the water in sand dams adheres to World Health Organisation (WHO) [27] guidelines for maximum thermotolerant coliform (TTC) concentration

Summary

Introduction

Two major expected impacts of climate change in semi-arid regions such as southeast Kenya are temperature rises and recurrent drought [1] These changes in climate are predicted to result in shorter more intense periods of precipitation, as opposed to the longer rainy seasons as historically experienced [2]. This will have a detrimental effect on the socioeconomic development of rural areas as they are dependent on rainfall for crop irrigation: agriculture forms the bulk of household income in the region [3,4]. The water is filtered when it passes through the sand, improving water quality in the same manner as a slow sand filter [7]

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