Shallow groundwater wells, are the main source of drinking water in many rural and peri-urban communities.
The quantity and variety of shallow wells located in such communities make them more readily accessible than private or government operated deep boreholes, but shallow wells are more susceptible to faecal contamination, which is often due to leaching pit latrines.
For this reason, online monitoring of water quality in shallow wells, in terms of faecal pollution, could dramatically improve understanding of acute health risks in unplanned peri-urban settlements.
More broadly, inexpensive online faecal pollution risk monitoring is also highly relevant in the context of managed aquifer recharge via the infiltration of either stormwater or treated wastewater into the subsurface for aquifer storage and recovery.
To tackle this challenge, IN-GROUND – an UPGro Catalyst Project – trialled four different types of Microbial Fuel Cell (MFC) water quality biosensor in the lab (Newcastle University, UK) and in the field (Dar Es Salaam, Tanzania).
While further work is needed, the results provided proof-of-concept that these biosensors can provide continuous groundwater quality monitoring at low cost and without need for additional chemicals or external power input.
“Over 300 million people worldwide use groundwater contaminated with arsenic or fluoride as a source of drinking water. The Swiss Federal Institute of Aquatic Science and Technology (Eawag) has developed a method whereby the risk of contamination in a given area can be estimated using geological, topographical and other environmental data without having to test samples from every single groundwater resource. The research group’s knowledge is now being made available free of charge on an interactive Groundwater Assessment Platform (GAP). enables authorities, NGOs and other professionals to upload their own data and generate hazard maps for their areas of interest.” More..
Other interesting and recent research and reports on fluoride and arsenic in groundwater:
Yes! It is very interesting for these kids, obviously amazed by the strange equipment put into the water. As soon as I started to set up the probes and to do the water quality measurements, I was suddenly surrounded by children, getting closer and closer trying to find out what is this about. It was in Osunyai Street, where I took a sample from a borehole close to Sombetini Primary School. The children are students of this school and they were just walking around when I arrived to continue with my data collection. The T-GroUP Project gave me the opportunity to mix my technical background in chemistry and water quality with social science, an exciting challenge with an interesting experience working in the field.
We all know that access to sufficient clean water is vital for sustaining life. For us humans, the ideal scenario is that everyone can go to a tap in their house, turn it on, and an endless supply of clean water pours out. But currently more than 700 million people worldwide do not have ready access to an improved water source, and instead rely on other water sources including lakes, streams, and unprotected hand dug wells. While access to piped water is on the highest rung of the “water ladder”, these other sources are of more variable quality. I’ve recently been working on a project which looks at the role that shallow hand dug wells play in water supply in urban settlements in western Kenya.
The UPGro Hidden Crisis project, led by Prof. Alan MacDonald at BGS, has already made an impact in its first study country – Uganda. Each year, the Ministry of Water and Environment coordinates a Joint Sector Review (JSR) and produces a Sector Performance Report (SPR) which reports on progress in the water and environment sectors and identifies the priorities head.
The 2014 report picked up on the work in the Catalyst phase and the further investigations by WaterAid into the problem of high iron levels in borehole water – largely due to inappropriate pump and pipe materials. The installation of cast iron or galvanised iron materials in acidic groundwater (ph <6.5) is largely preventable but all too common in many areas of the world. It leads to premature failure of the pump and makes the water unpalatable, or even unusable.
Dr Sharon Velasquez Orta (Newcastle University) has been recognised by the MIT Technology Review as one the leading “Innovators under 35” for 2015 for her work on developing a low-cost biosensor of measuring groundwater quality. In the UPGro Catalyst project (INGROUND), she and colleagues from Newcastle University and Ardhi University have been developing the sensor in the lab and trialling it in Tanzania:
“Her biosensor detects fecal contamination in water reserves destined for human consumption”
“In low resource areas, like sub-saharan Africa, the absence of water quality data poses a serious risk. For this reason, Sharon Velasquez has harnessed the degradation process undertaken by some organic bacteria to generate electricity which allows her biosensor to detect fecal contamination within the water source.
“The microbial fuel cells (MFC) that Velasquez uses work like batteries, the difference being that with MFCs the current flow is generated by the electrically charged components that batteries produce upon charging.
“In this way it is possible to create sensors that detect the organic material present in the medium as the bacteria begins to metabolize the organic material.
“Velasquez´s biosensor is characteristic due to its cylindrical shape which allows the resulting chemical reaction to happen directly in the environment.
“This technology aims to address the issue of fecal contamination of water supplies, given that this cannot be continuously controlled via existing systems because the detection process is lengthier and requires greater human resources.”
The INGROUND project is due for completion later this year.
The outbreak of Ebola virus disease in West Africa in 2014 is the worst single outbreak recorded, and has resulted in more fatalities than all previous outbreaks combined. This outbreak has resulted in a large humanitarian effort to build new health care facilities, with associated water supplies. Although Ebola is not a water-borne disease, care facilities for Ebola patients may become sources of outbreaks of other, water-borne, diseases spread through shallow groundwater from hazard sources such as open defecation, latrines, waste dumps and burial sites to water supplies. The focus of this rapid desk study is to assess from existing literature the evidence for sub-surface transport of pathogens in the context of the hydrogeological and socio-economic environment of Sierra Leone. In particular, the outputs are to advise on the robustness of the evidence for an effective single minimum distance for lateral spacing between hazard sources and water supply, and provide recommendations for protecting water supplies for care facilities as well as other private and public water supplies in this region.
Preliminary conclusions were:
Considering the climate (heavy intense rainfall for 8 months), the hydrogeological conditions (prevalent shallow and rapidly fluctuating water tables, permeable tropical soils), the pervasive and widespread sources of hazards (very low improved sanitation coverage), and the widespread use of highly vulnerable water points there is little evidence that simply using an arbitrary lateral spacing between hazard sources and water point of 30 – 50 m would provide effective protection for groundwater points. An alternative framework that considers vertical as well as lateral separation and the integrity of the construction and casing of the deeper water points is recommended to protect water supplies from contamination by pathogens.
The shallow aquifer, accessed by wells and springs, must be treated as highly vulnerable to pollution, both from diffuse sources and from localised sources. Diffuse pollution of groundwater from surface-deposited wastes including human excreta is likely to be at least as important as pollution from pit latrines and other point sources, given the low sanitation coverage in Sierra Leone.
Even though conditions are not optimal for pathogen survival (e.g. temperatures of >25° C), given the very highly permeable shallow tropical soil zone, and the high potential surface and subsurface loading of pathogens, it is likely that shallow water sources are at risk from pathogen pollution, particularly during periods of intense rainfall and high water table conditions.
Extending improved sanitation must be a high priority, in conjunction with improved vertical separation between hazard sources and water points, in order to reduce environmental contamination and provide a basis for improved public health.
We recommend that risk assessments of water points are undertaken for health care facilities as soon as possible including: detailed sanitary inspections of water points within the 30 – 50 m radius suggested by the Ministry of Water Resource; assessments of the construction and integrity of the water points; a wider survey of contaminant load and rapid surface / sub surface transit routes within a wider 200 m radius of water points.
Analysis of key water quality parameters and monitoring of water levels should be undertaken at each water point in parallel with the risk assessments. The translation of policy on water, sanitation and hygiene into implementation needs complementary research to understand key hydrogeological processes as well as barriers and failings of current practice for reducing contamination in water points. A baseline assessment of water quality status and sanitary risks for e.g. wells vs boreholes, improved vs unimproved sources in Sierra Leone is needed. Understanding the role of the tropical soil zone in the rapid migration of pollutants in the shallow subsurface, i.e. tracing rapid pathways, and quantifying residence times of shallow and deep groundwater systems are key knowledge gaps.
Photo: A well close to the community care facility at Kumala Primary School, Sierra Leone. Used with permission for the report from Enam Hoque (Oxfam).
Across much of Africa, cities are growing quickly. Current projections estimate that by 2050, 60 per cent of the population will be living in urban areas – half of them in slums. Many of these people have little access to services such as clean water and sanitation, and the UN has identified fixing this as a major priority.