Large-scale survey of seasonal drinking water quality in Malawi using in situ tryptophan-like fluorescence and conventional water quality indicators

Ward, Jade S.T.; Lapworth, Daniel J. ORCID: https://orcid.org/0000-0001-7838-7960; Read, Daniel S. ORCID: https://orcid.org/0000-0001-8546-5154; Pedley, Steve; Banda, Sembeyawo T.; Monjerezi, Maurice; Gwengweya, Gloria; MacDonald, Alan M. ORCID: https://orcid.org/0000-0001-6636-1499. 2020 Large-scale survey of seasonal drinking water quality in Malawi using in situ tryptophan-like fluorescence and conventional water quality indicators. Science of the Total Environment, 744, 140674. 12, pp. https://doi.org/10.1016/j.scitotenv.2020.140674

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Official URL: http://dx.doi.org/10.1016/j.scitotenv.2020.140674

Abstract/Summary

Faecally-contaminated drinking water is a risk to human health, with the greatest risks to those living in developing countries. UN Sustainable Development Goal 6 aims to address this issue. Tryptophan-like fluorescence (TLF) shows potential as a rapid method for detecting microbial contamination in drinking water, which could reduce the spread of waterborne diseases. This study is the first to investigate the effectiveness of TLF for a large-scale survey using a randomised, spot-sampling approach. The large-scale survey took place in Malawi, sub-Saharan Africa, in the dry season (n = 183). A subset of sources were revisited at the end of the following wet season (n = 41). The effectiveness of TLF was assessed by comparing TLF results to thermotolerant coliforms (TTC), humic-like fluorescence (HLF), inorganic hydrochemical data and sanitary risk scores. The most prominent differences in microbial water quality were observed between source types, with little variation between districts and seasons. TLF, TTCs, turbidity and sanitary risk scores were all elevated at alternative sources (shallow wells and tap stands) compared to hand-pumped boreholes. In the dry season, 18% of hand-pumped boreholes showed TTC contamination, which increase to 21% in the wet season. Groundwater recharge processes are likely responsible for seasonal variability of inorganic hydrochemistry at hand-pumped boreholes. TLF was able to distinguish no and low WHO risk classes (TTC 0–9 cfu/100 mL) from medium, high and very high risk classes (TTC 10 – >1000 cfu/100 mL). TLF failed to distinguish between no and low risk classes, which limits the use of TLF for assessing water quality to drinking water standards. This dataset indicates that HLF may raise baseline TLF for samples with low TLF values, increasing false positives. Therefore, TLF is better suited as a rapid high-level water quality screening tool to assess moderate and high levels of faecal contamination.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1016/j.scitotenv.2020.140674
UKCEH and CEH Sections/Science Areas:	Soils and Land Use (Science Area 2017-)
ISSN:	0048-9697
Additional Keywords:	groundwater quality, risk assessment, rapid screening, humic-like fluorescence (HLF), microbial contamination, drinking water, GroundwaterBGS, Groundwater, International development, Groundwater and health
NORA Subject Terms:	Hydrology
Date made live:	07 Aug 2020 13:12 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/528314

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1016/j.scitotenv.2020.140674

UKCEH and CEH Sections/Science Areas:

Soils and Land Use (Science Area 2017-)

ISSN:

0048-9697

Additional Keywords:

groundwater quality, risk assessment, rapid screening, humic-like fluorescence (HLF), microbial contamination, drinking water, GroundwaterBGS, Groundwater, International development, Groundwater and health

NORA Subject Terms:

Hydrology

Date made live:

07 Aug 2020 13:12 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/528314