The plants will have capacity of 240,000 cubic meters of water per day and will be completed in less than 18 months, Abdulrahman al-Fadhli wrote in a Twitter post.
The project, which the minister said was ordered by King Salman in a royal decree, will help government-owned Saudi Saline Water Conversion Corp (SWCC) raise production efficiency and cut operating and capital costs, Fadhli added.
He gave no details on funding.
Saudi Arabia said in 2016 it planned to use public-private partnerships (PPP) with local and foreign companies to fund infrastructure projects.
In August, it said it would develop resorts on about 50 Red Sea islands, completing the first phase of that project - which is backed by its Public Investment Fund (PIF) - in the fourth quarter of 2022.
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