MOMenTUM: MObile Microbial waTer qUality Monitoring using DNA technology

Interactive MapWithin the Momentum project we developed a field method, Orvion Udetect®, to be able to detect bacterial species of interest in water samples within 2 hours by qPCR. The method was used in Mozambique to produce quantitative and accurate data on the microbial water quality of the city of Tete (Nhartanda Valley). Informal settlements and industrial activities in and around the Valley threaten the water quality of the aquifer that is used as source of drinking water for the city. The aim of the project was to determine the general microbial water quality in different water sources around the Valley and to help visualise the effect of wastewater runoff and industrial activity on microbial water quality.

Consult, a total of 631 samples were analysed over four sampling rounds in 2019 and 2020. Each sample was tested with Orvion Udetect for two faecal indicators, Escherichia coli and Bacteroides dorei, and one potential human pathogen, Salmonella spp. In this way 1,893 data points were generated in total. Samples were also analysed for pH, conductivity, nitrate and ammonium using handheld sensors. Samples were divided into four water types, groundwater, surface water, tap water and (shallow) wells, to show the changes in water quality along the water system of the city (surface water à aquifer à users). The results were visualised in an interactive map (geo-mapping) to help show hotspots of faecal contamination and poor water quality.

Faecal indicators

60% of samples tested positive for E. coli, 18% for B. dorei and 5% for Salmonella. B. dorei is a faecal indicator that is more specific for human faecal contamination. These results show that other sources of faecal contamination (most likely livestock) are also relevant. This helps determine the most likely source of faecal contamination in a sample and to identify fitting preventative measures.

Some samples tested negative for E. coli, but positive for Salmonella (6 samples) and/or B. dorei (14 samples). This clearly demonstrates the importance of monitoring for different types of bacteria to make a better assessment of microbial water quality instead of relying solely on E. coli. An important benefit of Udetect is that it is possible to test for various microbial targets at the same time without having to change methods or procedures.

Water tapWater sample types

Wastewater and open defecation are the main sources of microbial contamination, and without a sewer system, the concentrations of microbial faecal indicators are, as expected, alarmingly high. About 60% of the surface water used to bathe in and wash were found positive for both faecal indicators. 25% of drinking water samples – groundwater, wells and taps – tested positive in all rounds for at least one microbial target (2% of samples contained more than 10,000 cells/100 ml). This data supports the need of preventative measures (such as dams, sand filters, public toilets) in the valley to improve water quality and protect drinking water sources and helps to identify hotspots that require the most urgent action. Monitoring in time will help determine their effectivity.

Tap water was found contaminated only occasionally. It remains to be determined whether faecal contamination is a matter of poor water quality, or poor hygiene and sanitation (or both). Only then can the best course of action be determined to improve drinking water quality.

Groundwater was not found to be significantly contaminated. This could be due to the depth of boreholes and piezometers that were sampled as well as dilution factors. Also, there is a protective clay layer above the aquifer that forms a barrier between wastewater runoff and the drinking water aquifer. It is known that in some areas this protective barrier has been removed as a result of industrial activities and that the aquifer in that area has become contaminated.

Other parameters for faecal contamination

Kaart

Ammonium and nitrate are parameters that are sometimes used as indicators of faecal contamination. However, the data generated within Momentum clearly demonstrates that there was no correlation between concentrations of ammonium and/or nitrate and the concentrations of faecal indicator bacteria. These chemical parameters are not able to replace monitoring of the microbial water quality.

The added value of the Udetect method is the wide choice of targets, the speed of the analysis and the digital, quantitative results that are generated. The mobile DNA technology can be applied in rural contexts, also for WASH studies and outbreak management, by being flexible in available targets and speed of analysis, both very important aspects in such contexts. The Momentum project was crucial for the development, validation and upscaling of Udetect ready for market introduction. As of October 2020, Orvion Udetect® is commercially available for monitoring of drinking water, surface/bathing water and (contaminated) groundwater. www.udetect.eu

Momentum received funding from Partners Voor Water a programme of the Netherlands Enterprise Agency (RVO) and the Netherlands Water Partnership (NWP) on behalf of the Ministries of Infrastructure and Water Management, Economic Affairs and Climate, and Foreign Affairs.

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