Consider This Before Investing In Desalination

Desalination is an increasingly attractive tool to mitigate drought-associated risks. Gerrit van der Merwe and Hermias Nieuwoudt spoke to Glenneis Kriel about some important factors to take into consideration before installing a filtering plant.

- Glenneis Kriel

Desalination is usually considered too expensive for farms. However, the expectation that climate change will result in more extreme weather patterns, particularly dry climatic conditions, is causing many farmers to re-evaluate the technology.

Gerrit van der Merwe, who produces onions and potatoes on 80ha at Knapdaar Boerdery near Piketberg, invested in a desalination plant seven years ago when he became worried about the reliability of water supply from the Boesmans River.

“The river accounts for all our irrigation water, but some years it dries up before our production season is over. A shortage of water could ruin our entire crop,” he says. To alleviate this risk, he installed a desalination plant to render his brackish borehole water suitable for onion and potato irrigation.

While the technology has helped to reduce production risks, especially over the past three years’ drought, Van der Merwe has faced much unnecessary expense.

“There are quite a few things I’d have done differently if I’d only known better,” he admits.

He and Hermias Nieuwoudt, head of new business development at NuWater, a company specialising in reverse osmosis water treatment plants, have the following advice for farmers wanting to install a desalination plant.

WATER QUALITY

First, get your water analysed by a recognised, independent laboratory. “The laboratory has to identify the salt content and suitability of the water for desalination,” says Van der Merwe. “Ideally, the water should only have a high level of salt. Added treatments, for example to rid the water of metals such as iron in my case, will drive up costs.”