Making lake water safe to drink – an innovative approach to tackling fluorosis
Brian McSorley WASH Coordinator
22nd Mar 2012
Oxfam is working with US engineers to develop a pioneering desalination solution in order to prive safe drinking water in rural Kenya. Brian McSorley reports on the pilot, in the last of his blog posts for World Water Week.
Drinking water across large areas of the East African Rift Valley, from Tanzania though Kenya and Ethiopia, contains excessive fluoride. In low concentrations fluoride has beneficial effects on teeth, but prolonged consumption of high-fluoride water leads to mottling and weakening of teeth, and even serious deformation of bone structure. Children are particularly susceptible.
Because fluoride has no taste, and because it is a chronic problem with no immediate adverse health impacts, it has largely gone unaddressed.
The place most affected by fluorosis in Kenya is the village of Longech. It depends on lake water and water from shallow wells, both of which contain fluoride concentrations of 20 mg/litre, over 13 times the World Health Organization (WHO) recommended limit. No simple solution exists but back in 2008 we in Oxfam decided to have a go. We engaged with a US-based engineering company to develop a manually operated desalination unit based on reverse osmosis technology to remove fluoride and other salts
from the water. This system, called "The Protector", was installed in Longech in September 2010 and we have been developing it and monitoring the results.
What we have found is that technically, it certainly does work; it dramatically reduces fluoride, almost to (maximum) WHO-recommended levels. Unfortunately we haven't yet been able to find ways to make the unit work sufficiently well to make it viable. The original design criteria envisaged that either one adult or two children could operate the unit, and fill a 20-litre jerrycan in two minutes without too much effort. However, in reality it takes four adults more than five minutes of strenuous effort to fill the jerrycan.
We continue to work with the developer to try to improve the unit, for example trying lower pressure membranes, adjusting the gearing ratios? etc, but we are also exploring other possible options. Finding a water treatment solution for Longech would have far-reaching benefits for communities throughout the Rift Valley. Generally too, in a world increasingly facing resource constraints, and with greater climatic variability, salinity in water is likely to increase, which increases the urgency of finding ways to utilise water that is currently considered unfit for human