Contractors have begun work replacing gas and water mains in Tawa St in Gonville.
The current 600 metres of water main on Tawa St (between Rata St and Kings Ave) was being replaced as it had reached the end of its useful life, the Whanganui District Council said.
The main provides water supply to surrounding residents and contributes to other Gonville areas.
At the same time, the gas main will be replaced using the same trench.
The project by Whanganui District Council and GasNet is part of a wider programme of works within the council's long-term plan and water asset management plan to upgrade the level of service available through the network.
Downer is the contractor.
The council said the project would increase the life of the mains and improve the level of service.
It would also help firefighting by increasing the flow and pressure capacity of the water.
The work was expected to take about six weeks to complete, finishing around June 24.
There would be traffic management in place reducing speeds to 30km/h with some stop-go at intersections.
Residents had been notified as the work might temporarily restrict access to driveways, the council said, and the water might need to be turned off at various times.