WORK is about to begin on a major new water tank to supply households across the central Borders.

As part of the £30 million upgrade of services, Scottish Water engineers will start constructing the large clear tank - which can hold five Olympic swimming pools worth of water - next to the A7 outside Selkirk.

The utility firm has already laid two thirds of the new pipes required for the upgrade along a seven-mile route between Selkirk and Galashiels.

The work will deliver improved treatment processes, environmental benefits and a more resilient supply to 20,000 homes and businesses in areas including Selkirk, Galashiels, Melrose, Lauder, Fountainhall and Newtown St Boswells.

Customers in these areas are now being notified of the introduction of a new water treatment process called chloramination as part of the upgrade.

Chlorine has been traditionally used for many years to keep drinking water safe.

But the chloramination process lasts longer in the pipe distribution system and lowers the levels of chlorine in water coming out of the tap.

Scott Fraser, communities manager at Scottish Water, said: “We are starting the chloramination process in the Borders to ensure our customers continue to receive a reliable supply of high quality drinking water.

"Chloramination is a tried and tested way of delivering this which and is already used in the supply to more than a quarter of our customers across Scotland."

Customers in Selkirk, Melrose, Lauder and some of Galashiels, served by Howden Water Treatment Works will have their supply changed over towards the end of February.

Customers in other areas – including the West of Galashiels and Fountainhall – will start getting water treated with the new process later in the year.

Scottish Water has written to affected customers letting them know that the change was due to take place.

A further part of the £30 million upgrade is the installation of new filters at the Howden Treatment Works, which will force up to 14 million litres a day through 0.4 micrometre wide straws - 25 times narrower than the thickness of cling film.

Manse Street Water Treatment Works, to the west of Galashiels, will be also switched off next year and converted into service reservoir to help to improve flows in the Caddon Water during dry summer periods.