Rutland County Council has warned emergency repair work on a well-known Oakham landmark could take up to a week to complete.
A Severn Trent water main crossing Swooning Bridge in Uppingham Road developed a leak last week, and engineers are working to repair it.
Houses on the Uppingham side of the bridge, dating back to the 1800s, have suffered low water pressure due to it.
Traffic is being diverted along Stamford Road while work continues.
Councillor Janine Rodger said: "Due to the age of the bridge, which dates back to the 1800s, carrying out repair work is proving difficult as the concrete is extremely tough.
"We initially hoped for a 24-hour closure, but it's already looking like that could stretch well into next week."