Owners of boreholes urged to be responsible water users

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boreholes
Drilling in progress. The team is preparing to measure the airlift yield of the borehole.

Frequent spells of drought – combined with the uncertainty of municipal water supply – are leading more South Africans to invest in their own boreholes. However, SRK Consulting warns that these water sources still require responsible management.

While boreholes help many people to either go off the grid or supplement municipal water supply, thereby lightening the load on strained municipal water systems, the groundwater sources being exploited are not infinite. According to Riona Kruger, principal geoscientist in SRK Consulting’s Port Elizabeth office, awareness is growing that South Africa is water-scarce and every drop needs to be conserved.

“No longer are producers the only ones making use of borehole water, but an increasing number of urban residents are having boreholes sunk on their properties,” said Kruger. “This is a great idea, especially where municipalities are battling to supply citizens with enough water to sustain a living.”

The importance of monitoring boreholes

Water being airlifted from the borehole during drilling.

She highlighted, however, that boreholes add to the pressure put on groundwater resources, leading to less water being available for each user. The key is for borehole yields to be professionally assessed, and for only a sustainable volume of water to be pumped out.

“The groundwater environment is mostly quite unpredictable, and each aquifer reacts differently to abstraction,” she said. “The best way to manage the use of groundwater is to have scientific yield testing done on each borehole to establish its actual yield capacity.”

The average groundwater user usually does not do this, she notes. Another essential management tool is that every borehole should be subject to regular water level monitoring, irrespective of whether a household, a large farm or an industrial company uses it.

“Boreholes need regular monitoring if their performance is to be reliable and sustainable,” she said. “They are also expensive to install and equip, so it makes sense to manage them closely. This means knowing how much water can safely be taken from the borehole and how the abstraction influences the water level in the aquifer.”

The ins and outs of monitoring a borehole

This diagram illustrates how the water level in a borehole would be measured.

To monitor changes in the water level of the borehole, a water level meter can be used manually or installed (automatically records measurements regularly). If these readings are plotted on a graph, it is possible to see whether the volume being pumped is sustainable, or whether the level drops constantly.

“Should you notice that the water level is declining over time, you should reduce the volume of water you pump from the borehole until the decline is halted,” said Kruger. “If the water level remains constant over time, the yield you are pumping is sustainable.”

She advised that the volume of water that an aquifer can yield over time can change, depending on various factors. The main one is the recharge rate, which depends on rainfall levels. The number of new users introduced to the aquifer will also have an impact. Changes in the borehole itself, such as the clogging of fractures leading into the borehole, can also affect volumes.

A last word

“People often need to be reminded that, while the hole and its infrastructure may be the property of the owner, the water remains the property of the state,” she said. “This places the onus on the user to manage the resource responsibly and not to the detriment of others.”

This graph illustrates the potential results obtained from a borehole where the water level is slowly declining. This means that the pumping rate should be slightly lowered until the graph starts to stabilise.

She urged all borehole owners to conserve South Africa’s precious underground water sources by monitoring their boreholes and not over-abstracting water volumes. – Press release, SRK Consulting