Scottish Water has started the next key phase of a £120m investment in the drinking water network which will benefit more than 200,000 people and businesses in much of Ayrshire and parts of East Renfrewshire.

The utility first announced in December 2015 that it would improve the water supply network by installing more than 30 miles of new water mains to connect the system in Ayrshire with the Greater Glasgow area’s network.

Customers across a large part of Ayrshire currently receive their water from a single source, the Bradan Water Treatment Works, south of Straiton in South Ayrshire.

The water is supplied to customers’ taps via a 34-mile-long trunk water main installed about 50 years ago which runs from the Bradan Water Treatment Works to a point north of Irvine.

The construction of the new strategic water main, which is expected to be completed in 2020, will connect the Bradan water supply network to the network served by the Milngavie and Balmore water treatment works, north of Glasgow.

When complete, the investment will enable Scottish Water to transfer water from Glasgow to Ayrshire, and vice-versa, if required, creating a larger, more robust and connected supply zone.

Work is about to be completed this summer on the first phase, which involved the construction of a 13 mile-long strategic water main, from near Newton Mearns, East Renfrewshire to the Fenwick/Waterside area in East Ayrshire, and a pumping station at Darnley.

The project is now moving on to the second phase which will involve the construction of another stretch of strategic water main, also about 13 miles long, which will be installed from the Amlaird Water Treatment Works in the Fenwick/Waterside area to Highlees Pumping Station near Dundonald in South Ayrshire.

The work - the Highlees project - which will include the construction of a pumping station near the Grassyards interchange at Ralstonhill east of Kilmarnock, is expected to be completed in about 20 months.

The work will complete the link between the Bradan and Milngave Water Treatment Work systems and enable water to flow in either direction.

The pipe, which is made of 900mm steel with a polyethylene external coating and an epoxy internal lining, will be installed in 13.2m long sections.

The work on the first phase included the construction by aBV of the Gorbals Pumping Station, in Darnley, which will pump water from Glasgow to the first section of pipe from near Newton Mearns to Fenwick. The second phase is being carried out for SW by Caledonia Water Alliance (CWA).

Other parts of the strategic water main will be a section of about six miles to be installed from the Pollok area to a reservoir storage tank in the south of Glasgow and the installation of more than seven miles of new water main in the Irvine area, which is progressing.

. Stewart Davis, Scottish Water’s programme manager, said:

“This is a massive investment in improvements to the water main infrastructure by connecting the system in Ayrshire with Glasgow’s network and we are having to do it in several key phases.”

“We are delighted to be in the final stages of the first phase, which involved some challenging work in difficult conditions, and we have now moved on to preparatory work for the start of the second phase with the first stretches of pipes due to be installed very soon.”