The burst water main is on The Street in the village of Butley, with Anglian Water saying that people are experiencing very low water pressure or none at all.
It is also along the route for the Tour of Britain, with the race expected to pass through the village at around 12.12pm this afternoon.
The road has been closed by the water company since 9.30pm yesterday.
On their website, they have said: “We’ve had to extend our repair time because it’s proving more complicated than we first expected. Our team on the ground is working as fast as they can for you.”