A street in Radlett that was closed after concrete was blocking the sewer has reopened.
The work on Watling Street, from Park Street roundabout to Watford Road, has been completed and the road is now under two way lights until Friday.
During the work Thames Water found the sewer has been completely blocked by concrete causing sewerage to back up and a full replacement of the sewer was required where the concrete is causing the obstruction.
Terry Douris, cabinet member for highways at Hertfordshire County Council, said: "We are extremely frustrated that this situation has arisen due to what appears to be someone’s irresponsible actions and residents affected by this disruption have our sympathy. Due to the nature of these works council taxpayers will not be footing the bill."