12th October 2021: Scientists have developed a reliable new method to monitor the risk of contamination in drinking water which gives immediate results, enabling global communities to respond rapidly and help reduce their exposure to waterborne diseases.

Drinking water contaminated with human and animal faeces is consumed by at least two billion people worldwide. This pollution is responsible for outbreaks of waterborne diseases that remain common, even in high-income countries.

For decades, standard approaches to test water supplies have used bacteriological indicators of faecal contamination, most commonly thermotolerant coliform bacteria known as TTCs. Analysis of these indicators requires use of sterile equipment and culturing techniques, which practically limit the frequency of water sampling so that contamination events can be missed. Time lags of 1 or 2 days before results are returned mean that people can already have been exposed to the faecal contamination.

A new study, published this week in Water Research by a collaborative team from Makerere University, the British Geological Survey, and University College London, shows how a technique exploiting the fluorescent properties of microbiological materials in water provides an easy-to-use method to test for faecal contamination.

Co-author Jacintha Nayebare, PhD student at Makerere University said, “In-situ fluorescence spectroscopy provides an instantaneous assessment of faecal contamination allowing rapid feedback to consumers that could reduce exposure of consumers to faecally contaminated drinking water.”

The team examined changes in water quality over a 14-month period from 40 sources supplied by groundwater in Lukaya Town of south-central Uganda. The results show not only that in-situ fluorescence provides an instantaneous measure of faecal contamination but also that it is a more reliable measure of the risk of faecal contamination than TTCs.

Co-author, Dr. Robinah Kulabako from Makerere University’s Department of Civil and Environmental Engineering said, “this rapid, robust method of monitoring the risk posed by faecal contamination has enormous implications in Uganda not only for untreated water sources such as wells and springs thereby, enabling communities to respond rapidly to contamination events but also for low-cost, continuous monitoring of piped water supplies.”  

This research builds upon field studies conducted by the team in a network of urban observatories in Senegal, Kenya and Uganda under the AfriWatSan project, supported by The Royal Society and DFID, as well as research in the UK, India, and Zambia funded by Natural Environment Research Council.

Lead-author, James Sorensen from the BGS and UCL said: “the ability to test in-situ fluorescence as an indicator of faecal contamination risk in a wide range of environments and conditions has greatly improved both the evidence base for this method of water quality monitoring and our understanding of what fluorescence observed in water means.”