About 45,000 Saint John residents are being asked to boil their tap water due to a water main break on the city’s east side.

The culprit cast-iron pipe was placed in the ground about 140 years ago and is a key line connecting the municipal reservoir and city core.

“The vintage of the pipe was approximately mid-1800s,” says Deputy Works Commissioner Kendall Mason. “It appears to be an 1873 vintage cast-iron pipe.”

Because of the main break, the city could not guarantee that the water in the system was properly chlorinated, resulting in the boil order.

The boil order forced the closure of operating rooms and outpatient clinics at St. Joseph’s Hospital. The Horizon Health Network says the hospital closed its urgent care centre and has been diverting patients to the Saint John Regional Hospital.

Brenda Kinney, executive director of Saint John Regional Hospital, says staff from St. Joseph's transferred to her facility for the day and took in additional patients.

She says St. Joseph's continued to operate its diagnostic services during the day.

She says the city has informed the hospital the water main is repaired and it's expected St. Joseph's will reopen all services Wednesday.

At the local Boys and Girls Club, all water fountains were covered to prevent children from drinking from them. The boil order also affected operations in the kitchen.

“We feed 100 kids every day at lunchtime and everything we have to make that includes water we have to start boiling,” says Amy Shanks.

The water main break also affected Forest Hills schools, which closed due to low water pressure.

“Especially in a school because children are not able to use the washrooms, children can’t wash their hands,” says Doug Walker of the New Brunswick Health Department.

Boil orders have happened on a fairly regular basis in Saint John for years but steps are being taken to remedy the situation.

The city is embarking on its biggest municipal makeover – a $200 million infrastructure project.

“Besides the water treatment plant and new transmission mains, we’re also going to have water storage, so it will improve reliability and reduce interruptions in service,” says water project manager Dean Price.

However, construction is unlikely to begin before 2016 and the project will likely take three years to complete.

The city says the current boil order will remain in place until two consecutive tests done 24 hours apart show the water is safe to drink. It is expected to remain in place until late this week.

The boil order applies to areas east of the Reversing Falls Bridge.

With files from CTV Atlantic's Mike Cameron and The Canadian Press