The Somerset group of companies, includes Northavon Water Services, Hydrovein, and Multivein.
Jointly, the group turns over around £32m, operating primarily in the water sector in the South of England and South Wales.
The acquisition of the Midsomer Norton based-group will support OCU’s growth across the water and wastewater sector as the group continues its fast-paced expansion in water and energy markets.
The deal will also give £300m revenue OCU a stronger regional presence across the south west.
Northavon employs around 150 staff providing a broad spread of services from mechanical, electrical, instrumentation and civils design to construction and installation of clean and wastewater treatment facilities and sewage pumping stations, together with maintenance services.
It also has divisions focusing on highways and groundworks.
Clients include South West Water, Thames Water, Wessex Water and Dŵr Cymru Welsh Water.
Completion of the deal is subject to regulatory clearance and is expected to occur in May 2023.
Michael Hughes, chief executive of OCU, said: “The water and wastewater sector is changing rapidly, and there are several factors we need to consider when operating in this area.
“As we head towards AMP8 in 2025, we need to innovate and increase collaboration across the industry in order to protect our water and waste-water infrastructure and support our customers achieve their own environmental goals.
“This latest acquisition will enhance the expertise our clients want and deserve. It’s an exciting time for OCU and I’m looking forward to working with Mike Clancy and the wider Northavon team as we expand our water and wastewater capabilities.”
Mike Clancy, group managing director of Northavon, said: “With less than two years to go until AMP8, we have huge potential to streamline ways of working to create an environment that both meets regulatory requirements and gives the best service for our customers.
“OCU is focused on growing across water and energy-related sectors to increase its expertise and support societal and environmental goals.
“We’re excited to now be part of the Group that shares our commitment to a greener and cleaner future and look forward to seeing what projects we can deliver together.”
The deal with Northavon marks the sixth and largest acquisition in just over 12 months for OCU.
It follows the acquisition of Modus, a London-based multi-utility specialist, InICT, a Leeds-based fibre-optic specialist, Opals, a regional multi utilities hub, Andrews Associates, a Surrey-based power systems design and engineering service, and FKS, a Wigan-based telecom installation service.
As part of the acquisition arrangements, Northavon will become known as OCU Northavon.