Numerous towns and communities depend solely on groundwater, and many towns use a combined supply of surface and groundwater. When the town or settlement is far from any surface water and groundwater is available, boreholes are drilled. Depending on the size of the settlement, the boreholes are equipped with electrical or hand pumps.
Most of the big cities use surface water in their water pipes. Almost all big cities worldwide are located close to a supply of fresh water. Cape Town has drilled many boreholes in the past two years to augment the city’s water supply. However, problems can arise when a borehole is drilled for a community with a certain number of people and soon there are many more people than the borehole can supply. It is not so much a case of the “borehole drying up” but that the capacity is exceeded.
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With increasing drought and water restrictions, many people opted for their own borehole. When so many people draw water from the same source, the water table will drop. It can be compared to drinking from a milkshake. When five people drink with straws from the same milkshake, everyone will be left thirsty.
Because groundwater is something that cannot be seen by the naked eye, the general public has many misconceptions about groundwater. Some people think that you can drill a hole just anywhere and that you will find water, others believe that water flows in underground rivers. It generally moves very slowly, only a few metres a year. And if it rains at a specific place, it does not mean that water will reach a particular borehole.
Sustainable groundwater usage is the certainty that enough groundwater is available in years to come. Sustainability is dependent on two external factors: demand and supply. Both factors are beyond the control of the geohydrologist. When enough water is available for a community, the chances are that the community starts to grow, thereby enlarging the demand. If the higher demand cannot be met, sustainability is no longer possible. When a change in rainfall pattern results in a decline in the precipitation, the groundwater recharge will become less resulting in a lower supply of water.
