Local MP Matt Turmaine has visited the site to see progress on the £12m preparation programme.
A huge crane has been brought to the site to remove a suite of temporary buildings.
The works will also include the installation of new oxygen supply systems, the demolition of old buildings and undertaking surveys and physical ground investigations over the next 18 months.
Watford General Hospital is one of nine Wave 2 schemes under the revised New Hospital Programme that was published by the Government in January 2025.
Construction of the hospital is estimated to begin between 2032 and 2034 with the project costing £1.5bn-£2bn.
