It’s time to start pumping for groundwater – but at what cost?

As Cape Town reaches a critical stage of drought, we look at whether tapping into groundwater is a viable alternative.

Ground Water

Cape Town and the entire Western Cape province were declared disaster managed areas in May this year. But that has not stalled water usage.

According to numerous reports, Cape Town is expected to completely run out of potable water by March of 2018.

Consequently, nine city suburbs – including Camps Bay, Parow and Constantia – have already experienced water outages, in addition to lowered water pressure. As officials scramble to solve this disaster, the extraction of groundwater is seeming like one of the most feasible answers to this potential catastrophe.

But what do we know about this resource?

In an August report for the Daily Maverick, Chair of the Western Cape branch of the Ground Water Division of the Geological Society Dr. Robert Parsons wrote, “Cape Town was established here because of groundwater. Springs discharging out of Table Mountain and flowing into what is now the City Bowl provided water to the refreshment station from which Cape Town grew.”

Reliably potable, there is also a host of other benefits that come with using groundwater. According to the World Health Organisation, it is likely to be free of pathogenic bacteria, can be used without further treatment, and, in many instances, can be found in the vicinity of rural communities, which are often affected the most in times of drought. Despite these advantages, groundwater is also often high in concentrated mineral content and requires pumping – the environmental implications of which should certainly not be ignored.

Ground Water

While groundwater is a viable alternative to our current source, it’s one that we need to utilise carefully. Though authorities have set a consumption target of 500-million litres a day of our current dwindling supply, consumption stubbornly remains at about 600-million litres a day, raising a valid question: will the Western Cape behave as carelessly with another source?

Because groundwater supplies are recharged naturally by rain and snowmelt, we can only abstract as much water as that being recharged, lest we run into deficit. If this were to happen, replenishing this source could take months, years or even hundreds of years. Additionally, the drilling of boreholes into aquifers on Table Mountain (one of the largest in the world) and on the Philippi Horticultural Area – something which the City of Cape Town has plans to do – could have a catastrophic impact on our environment, according to University of Cape Town professor Dr Kevin Winter

Over-extraction is the most significant danger. The pumping of groundwater at a faster rate than it can be recharged can lead to the lowering of the water table, increased costs for the user, reduction of water in streams and lakes, and a deterioration in water quality. “Tall trees (would start) withering, dying and falling over, as well as lakes and rivers ceasing to flow are the first signs of the over-abstraction of groundwater,” says Winter.

Aside from this, it will take a significant amount of time to drill, extract, test and analyse the water before it gets to the taps of consumers.

Ultimately what is needed is a significant shift in the attitudes of both residents and authorities when it comes water. It needs to be treated as a scarce resource regardless of where it is obtained from. Because the truth is, without some miracle rainfall, our reliance on alternative sources of water is simply unsustainable.