It will supply teams to Galliford Try, Costain, Tilbury Douglas, MWH Treatment, Glanua and Thames Water to support projects at clean and wastewater treatment sites nationwide.
Around £4.5m of work will be delivered in the Thames Water region, with another £1m each in Severn Trent and Anglian Water areas.
The contracts come as regulator Ofwat forecasts more than £104bn of spend between 2025 and 2030 on infrastructure upgrades, environmental improvements and resilience measures.
Hercules said it expects much more work to flow as contractors ramp up delivery across the country.
The firm is already active in the Anglian, Thames, Southern, Severn Trent, Wessex, United Utilities, Welsh Water and Yorkshire Water regions.
