Water Corporation and Rio Tinto agree to go halves on $1.1b Dampier desal to ease Pilbara water pressure

Rio Tinto and the State Government will both bear the cost of doubling the capacity of a $1.1 billion Pilbara desalination plant as the mining giant looks to reduce its burden on precious water supplies. Following concern from Traditional Owner groups and amid closer scrutiny of WA’s water usage, Rio got to work on building the first stage of the Dampier seawater desalination plant last year and is expected to start delivering on 4 gigalitres of capacity by the end of 2026. The 50:50 agreement revealed Wednesday between the listed miner and the Government will see another 4Gl of capacity added to the much-needed water infrastructure, following a period of negotiation on cost and feasibility between Rio and the Water Corporation. Construction has already started on the second stage of the plant with first water expected in 2027. Rio said rainfall in the West Pilbara over the past five years had been “below the long-term average” and put significant pressure on the Millstream and Bungaroo aquifers that supply the West Pilbara Water Supply Scheme — which covers the likes of Karratha, Wickham and Dampier as well as industrial areas on the Burrup Peninsula. Big miners such as Rio use the water in their iron ore operations for dust suppression, as well as in processing and for mining camps. WA is heavily reliant on groundwater, with about 78 per cent of all potable water across the State drawn from underground aquifers. Premier Roger Cook said the Government was ploughing hundreds of millions of dollars into a project that would “deliver billions of litres of water to local households and businesses”. Rio’s new iron ore chief Matt Holcz said the miner was working to reduce its reliance on groundwater extraction. “We understand water is a scarce resource, especially in the Pilbara. We are pleased to partner with the Western Australian Government to improve the security and sustainability of water supply.” The mining industry was allocated the largest proportion of licensed water volumes in 2024-2025, extracting 46 per cent, according to its most recent annual report. Water Corporation and Western Power are in the middle of building a $2.8b desalination plant in Alkimos.