Microbial water quality of treated water and raw water sources in the Harare area, Zimbabwe

Tatenda G Chirenda,Sunitha C Srinivas,R Tandlich

doi:10.4314/wsa.v41i5.

Abstract

Microbial water quality is an essential aspect in the provision of potable water for domestic use. The provision of adequate amounts of safe water for domestic purposes has become difficult for most municipalities mandated to do so in Zimbabwe. Morton-Jaffray Treatment Plant supplies potable water to Harare City and areas surrounding Harare. This study investigated microbial water quality and the impact of microbial water quality related disasters in the area supplied by the Morton Jaffray Treatment Plant. Questionnaires were distributed to household owners in Harare who receive their water from the Municipality and those who use alternate water supplies. Candidates were randomly selected from their workplace. The raw water quality of Manyame River and its tributaries was assessed. Treated water in households was assessed for microbial quality using hydrogen sulphide test and heterotrophic bacteria plate count. Raw water sources were found to be contaminated by faecal matter. Household water sources tested negative for faecal contamination but positive for heterotrophic bacteria. CFU quantities ranged from 1 to 452 CFU/m. for all samples. The WHO guidelines for domestic water sources state that water used for domestic purposes should not be contain than 100 CFU/m.. Public perceptions of water quality ranged from eunsafef to ehighly contaminatedf. A decrease in the level of aesthetic appeal resulted in residents resorting to alternative sources such as wells and rivers for their domestic water. The current state of treated water was suitable for domestic use. Pathogen monitoring of domestic water is recommended using the hydrogen sulphide test and R2A agar test.Keywords: microbial water quality, faecal contamination, H2S strip test, R2A agar test

Highlights

Water is an indispensable human requirement which is critical for development (WHO, 2012; World Health Organisation (WHO)/UNICEF, 2014)
Microbial water quality was assessed using the H2S test according to Venkobachar et al (1994) and Sobsey and Pfaender (2002) as modified by Luyt et al (2011) and heterotrophic bacteria plate count using R2A agar from SigmaAldrich (Johannesburg, South Africa)
River samples were found to be positive for faecal contamination based on the qualitative signals in the improved H2S test kit, which indicates that this water is not recommended for domestic purposes

Summary

Introduction

Water is an indispensable human requirement which is critical for development (WHO, 2012; WHO/UNICEF, 2014). The human right to water entitles everyone to sufficient, safe, acceptable and physically accessible and affordable water for personal and domestic use (OHCHR, 2015; WHO, 2015). The quantity must suffice to meet basic human needs in terms of drinking, bathing, cleaning, cooking and sanitation; the World Health Organisation (WHO) sets this volume at approximately 50–100l per person (WHO, 2015). The required minimum quality of household water is dependent on its specific use: drinking water must be safe for consumption whereas lower standards may be set for water for sanitation (Gleick, 1999; UN, 2015). In order for water to be affordable to all, the United Nations Development Programme (UNDP) suggests that water costs should not exceed 3% of the household income (OHCHR, 2015)

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Conclusion