Northumbrian Water is investing a total of £21 million on the two new works, which will be built in Murton, Berwick-upon-Tweed and Wooler.
Construction of the Berwick works will begin next month, following initial preparatory works on 14 November, with a view to the new site becoming fully operational in November 2019. Work in Wooler is anticipated to start next year (June 2019) and will also take up to 12 months to be complete.
Construction on both sites will carried out by Northumbrian Water′s delivery partners, Mott MacDonald Bentley.
The new water treatment works will use cutting-edge technology and processes to treat up to 12 million litres of water a day.
This will meet the needs of over 25,000 customers in the north Northumberland area, by providing a high-quality, reliable supply of water into the future.
Northumbrian Water′s Water Supply Area Manager for North Northumberland, Stuart Tilley, said: "This is a major investment to help improve our water infrastructure and protect supplies for our customers in these areas for many years to come.
"We′re committed to delivering an excellent customer experience and this project will make sure we can continue to provide excellent tap water quality."
Customers′ water supply will not be affected while the work is carried out, although there may be an increase in volume of traffic to the sites.
Residents will be able to follow the progress once work gets underway by visiting both the Wooler and Berwick pages on www.nwlcommunityportal.co.uk.