Farrans fought off stiff competition from rivals including Clancy Docwra for South East Water’s Burham and Swinley Forest Strategic Main.
Work is set to start on site in January.
The projects comprise the design and construction of 9.3km and 3.7km lengths of new water pipeline, replacing the existing ageing assets.
Works will take place over 40 and 76 week periods, concluding in Autumn 2015 and Spring 2016.
Farrans Director Kevin Corley said: “We are delighted to have been awarded these two significant projects which will build upon our existing portfolio of work for UK Water Authorities.
“We look forward to working closely with South East Water on both schemes and well into the future.”