Scottish Water has announced the completion of a £16 million upgrade to water treatment works (WTW) near Howwood in Renfrewshire which will benefit more than 84,000 people.

The two-year project at the Muirdykes WTW involved the installation of a new filtration building and process to reduce the risk in the network of discoloured water caused by naturally-occurring manganese.

Muirdykes WTW provides water for homes and businesses in Johnstone, Howwood, Linwood, Elderslie, Kilbarchan, Quarrelton, Craigend and some areas south of Paisley.

The project follows investment of £4 million four years ago in more than 100 miles of water mains affected by discoloured water in the county when acutting-edge piece of equipment called a Wears Resmix system was installed at Barcraigs reservoir.

The new secondary stage filtration process will remove oxydised manganese from the system before it goes into the supply zone and will be housed in a single-storey building constructed on the WTW site by contractors Black & Veatch.

Scottish Water had given an undertaking to the Drinking Water Quality Regulator to provide an effective manganese removal system for this area.

Joanna Peebles, Scottish Water’s regional community manager for the area, said: “While we cannot guarantee there will be no recurrence of manganese and discoloured water in the Muirdykes network, our upgrade of the WTW, in addition to the previous investment, will substantially reduce the risk.”

Manganese occurs naturally in rocks and soil but can become noticeable in tap water at concentrations greater than 0.05 milligrams per litre of water (mg/l).