South Africa is the 30th driest country in the world. Over 400 towns, especially in the western and central parts of the country, rely on water from aquifers that they pump out of the ground (groundwater).

A rural dam of brown, muddy water, about the size of half a soccer field and not very deep looking.

In 2018 an intense drought occurred in the Northern Cape province. Both dams and groundwater sources were depleted. Some towns, like Sutherland, passed “Day Zero” (the day water runs out) in 2021. To manage the crisis, the local authorities began water-shedding (shutting the water off except for a few scheduled hours daily).

But this is not a lasting solution as climate observations show that rain is falling later than expected every year, and is not replenishing groundwater enough.

In these dry areas, there is the possibility of another solution: managed aquifer recharge. This works by channelling surplus surface water into specially constructed basins, ponds or ditches. This water slowly seeps through the soil to recharge the aquifer. Water can also be pumped in.

We are groundwater scientists who study aquifers. In a recent paper, we discussed how managed aquifer recharge had refilled groundwater in the rural Karoo towns of Carnarvon, Vanwyksvlei, Williston, Sutherland and Calvinia. These towns rely on borehole water, but rain was not replenishing the aquifers enough for the towns to keep drawing water from them.

Our research sets out the specific approaches and successes of small-scale, low-cost schemes that used surplus rainwater to enhance the recharge of the aquifers.

We found that managed aquifer recharge delivered a number of benefits. These included improving water supply in the towns and improving the quality of the water.

There were also environmental benefits – some vegetation improved around some of the recharge sites. The vegetation stabilised the soil, allowing greater amounts of rain to filter back down into the aquifer instead of flowing away.

Our research shows that groundwater can efficiently make up for a water supply shortfall in small towns. Most managed aquifer recharge schemes elsewhere in the world are large and relatively high cost. We’ve shown that it’s possible to use the method effectively at small scale and at low cost.

How the small towns got their water supply back

An aquifer is like a underground dam. The bottom of an aquifer is like the bottom of the dam: if there is no more water in an aquifer it dries up, just like a dam. In all five projects, after being recharged, the aquifers water levels rose – in some cases, dramatically.

Carnarvon: population 7,400

In 2015, we drilled six boreholes to a depth of 12 metres through clay layers in the river bed. This was so that when it rained and the river filled up, the water would seep into the ground faster.

After continuous good rains since 2022, the aquifer water level rose from 24 metres below ground level (the bottom of the borehole) to 19 metres below ground level.

Williston: population 3,400

This small town’s current managed aquifer recharge scheme, set up in 1983 by the municipality and the Department of Water and Sanitation, is made up of check dams – barriers placed across rivers or channels to slow the movement of water. These check dams are in a river tributary and, together with the town dam, serve as basins from which water infiltrates into the ground.

A heavy rainfall event of 40mm in 2022 caused a 10 metre rise in the groundwater level. This amount of water sustained the town for two years.

Sutherland: population 3,000

We started a new managed aquifer recharge scheme in 2021 after the water supply ran out. Located at 1,450 metres above sea level, Sutherland offers exceptional dark skies, and hosts the Southern African Large Telescope (SALT), which attracts many visitors throughout the year. We needed to make sure there was enough water for the tourists and workers from new wind farms.

To do this, we placed gabions in the dry streams and man-made stormwater channels in Sutherland during 2021 to slow river flow during flash floods and enhance recharge.

A gabion is a basket filled with rocks. It is not cemented so it doesn’t create a solid wall and water can still flow through it. Here, the aquifer water level also rose by 10 metres between 2022 and 2023 after good rains.

Vanwyskvlei: population 1,800

Our managed aquifer recharge scheme has been able to provide reliable fresh groundwater to the town since 2019. The project consists of three infiltration boreholes that we drilled through dolerite, an impermeable rock that wasn’t allowing rain to filter through, into the shale rock formation where the water is stored.

The infiltration boreholes allowed large amounts of water to seep down into the aquifer when it rained.

Here too, the water levels in the aquifer rose substantially.

Calvinia: population 12,000

This town depends on both surface water and groundwater, which wasn’t enough after a drought began in 2015.

We set up a managed aquifer recharge scheme here in 2024 by installing gabions and infiltration boreholes in the stream channel. In 2025, a flood caused the water level in the aquifer to rise substantially.

Adapting to the changing climate by refilling aquifers

Our research shows that it’s possible to enhance aquifer recharge affordably with conventional water (rainfall or surface water). It’s best to drill the boreholes and build the other structures, like gabions and check dams, during a drought. That way, when it starts to rain, everything is ready for the depleted aquifers to receive a water recharge.

The cost can be as little as a strategically placed borehole (about R150,000 or US$8,915) or range up to a whole design scheme with engineering input costing R5 million (about US$300,000).

Managed aquifer recharge can also be done by using wastewater as source water to recharge into the aquifer. But we did not use any treated or untreated effluent as this could affect the microbial diversity in the aquifers and damage the water quality.

Our study shows that small-scale managed aquifer recharge schemes using conventional water sources are effective in providing a sustainable water supply to small rural towns in South Africa. We propose that they be included in national policy guidance on securing water supply in the water-scarce areas of southern Africa.

Expert Insights provided by Surina Esterhuyse, Associate Professor in the Centre for Environmental Management, University of the Free State, Danita Hohne, PhD Candidate in the Centre for Environmental Management, University of the Free State, and Fanus Fourie, PhD Candidate in the Institute for Groundwater Studies, University of the Free State. This article was originally posted on theconversation.com and is republished here under a Creative Commons license. Read the original article here.

Featured Image: Romanskolk, a farm near Brandvlei in the study area, showing what drought looks like. Courtesy Danita Hohne