Authorities in Kenya’s driest region are in talks with a Saudi investor to build a desalination plant, after hopes of finding drinking water from an aquifer were dashed.

Tito Ochieng, the director of water services in Turkana, in the north of the country, said the potential investor – Saudi-owned Almar Water – has already signed a deal to build a $160m (£125m) desalination plant in Mombasa.

According to Ochieng, the plant would be built on top of the Lotikipi aquifer, in the village of Nanam, and is expected to cost 5–10bn Kenyan shilling (£37.5–75m).

Ochieng said the partnership could be sealed “within a few months”. The investor is in the process of validating a business plan that would involve privatising the water and selling it to water companies, while subsidising access to water for the local population.

News of the Saudi interest followed a recent announcement by government officials that water held in an aquifer discovered six years ago was not suitable to drink.

The Lotikipi aquifer, discovered under the desert of Turkana in 2013, was estimated to hold 200bn cubic metres of water, enough to satisfy the needs of Kenya’s population for the next 70 years.

Turkana herders are driven to Uganda and Ethiopia in search of water and grazing land for their livestock. Photograph: Goran Tomašević/Reuters

The discovery of drinkable water would have been life-changing. About 80% of people living in Turkana, Kenya’s poorest and least developed county, do not have access to 50 litres vof water a day – the amount guaranteeing “that most basic needs are met”, according to the UN.

Since 2017, repetitive droughts have driven 60,000 nomadic herders to Uganda and Ethiopia in search of water.

But a government report from 2015 showed that the water from the aquifer was too saline for human consumption, with mineral levels seven times the accepted limit. This was based on data from one of three wells.

A hydrogeologist at Kenya’s Water Resources Management Authority, who wanted to remain anonymous, believes the original claims about the potential of the aquifer were too hasty, and lacked the necessary analysis. The water authority is now searching for other aquifers in the region and is expected to publish its findings soon.

However, Alain Gachet, the French engineer who discovered the aquifer, said it was too early to rule out the possibility of finding fresh water in the giant aquifer. Gachet believes that exploratory drilling should continue before moving on.

Daniel Nanok, the MP for Turkana West, agreed that the aquifer might still hold pockets of fresh water, but said he believes the desalination plant is a good option for the short term.

“It is too early to say that the whole aquifer is saline, but the local populations need the water now. Desalination is not a perfect solution but the pastoralists on the ground cannot wait six more years,” Nanok said.