65 meters of an existing sanitary sewer on Victoria Street in Alliston is being replaced.
The Town of New Tecumseth indicates contractors have already started with the design phase.
Crews will be using a closed circuit television camera to investigate the current sewer system.
Businesses and residents between MacDonald and Boyne streets are not expected to be impacted by the investigation.
The design phase is expected to be completed by January of next year.