Groundwater: a key resource for towns and cities around the world struggling to provide enough water for their thirsty residents.
It has many advantages over surface water, as it is often more reliable, nearer to households, less vulnerable to pollution, and more resilient to climate variability.
With urban populations in Africa and south Asia continuing to grow, we will need well managed aquifers if we are to have any chance of providing urban communities with access to safe water. Climate change is reducing water availability, particularly in surface water reserves but in many parts of the world, including Africa, groundwater reserves are estimated to be 20 times larger than the water stored in lakes and reservoirs above ground.
So groundwater can be a vital part of many countries’ climate adaptation strategies. And yet, are we valuing groundwater properly, and protecting it to ensure it can meet our needs?
The answer seems to be a clear, ‘no’.
WSUP’s experience across the countries where we operate is that we are not giving enough respect to groundwater.
Groundwater is being mis-used and mis-managed in urban areas through multiple ways, such as raw sewage seeping into the water, agricultural and industrial pollution, uncontrolled abstraction, and a lack of monitoring of water quality.
For example in Lusaka, where around 60% of the water supply comes from groundwater, around 83% of the sanitation waste is not properly managed, leading to significant contamination of the aquifer which runs underneath the city.
Just as in most cities on the continent, many people are reliant on pit latrines, often little more than a hole in the ground, where the waste seeps into the ground, and eventually, in the water supply.
In coastal areas, the growing threat of rising sea levels threatens groundwater supplies. Saline intrusion is where sea water gets into the underground aquifers, making the water undrinkable. In the coastal city of Chattogram, Bangladesh, we have seen evidence that boreholes are becoming unusable because of the saline intrusion.
In many countries, groundwater is being over-used, meaning that more water is taken from the aquifer than can be put back from rain or snow. Over time, the aquifer becomes depleted.
Across south Asia, groundwater levels have declined, causing issues for urban water supply. The cost of drilling and pumping is increased, with a disproportionate impact on the poor.
The absence, in many cities, of a single institution effectively managing water abstraction makes it very difficult this situation to be managed. In Africa, it is estimated that around one-third of the urban population uses so-called self-supply groundwater, usually in communities which have not been able to receive adequate service from the public water utility. In Lagos, Nigeria, for example, 51% of households own their own borehole.
In the short-term, self-supply groundwater enables under-served residents to get access to water; but this water is often untreated. In addition, over the longer-term, the uncontrolled abstraction of water can risk the health of the aquifer.
In Mozambique’s coastal capital Maputo, and the surrounding Matola city, where private water providers build boreholes which are dotted around the landscape, saline intrusion is a real risk as the aquifer becomes over-exploited.
Sometimes, the issue is not man-made – it’s a natural phenomenon. In Kenya’s Rift Valley, for example, the aquifer is contaminated with fluoride, excessive consumption of which can causes problems for bones and teeth. WSUP worked with private operators and the city utility in Naivasha ten years ago to ensure that water was treated to reduce fluoride levels down to recommended World Health Organisation levels.
Another commonly occurring chemical is arsenic, which is present in countries such as Bangladesh – requiring careful management to ensure arsenic-safe water supplies.
Groundwater is, by its very nature, invisible to the communities and the decision-makers that depend on it.
And yet, it is crucial. Healthy people depend on groundwater; depleted or contaminated aquifers will not help rapidly growing cities to become more prosperous and equitable places to live.
Improved management of sanitation waste; better monitoring; more oversight over water abstraction: all these will help protect groundwater for the benefit of people living in cities.
So let’s respect groundwater, so that we can meet one of humanity’s most basic needs – the need for safe, clean, water.