About 45,000 Saint John residents were hit with a boil water order early on Thursday morning after heavy rains caused the city's water to become cloudy.

The boil order is in place for all residents who live east of the Reversing Falls Bridge and comes a few days before the Thanksgiving long weekend.

The city is planning a news conference on Thursday to update citizens about the boil order affecting New Brunswick's largest city.

The heavy rain caused turbidity levels to go up, making the water cloudy, and the city's chlorination does not work effectively in that situation.

The boil order, which also affects businesses, was issued shortly after midnight on Thursday.

Saint John Water needs two clear tests that are taken 24 hours apart in order to lift the boil order.

City residents who are a part of the Emergency Alert System were notified of it around 2 a.m. by email, text message or voice mail.

While more chlorine has been added, residents are asked to bring their water to a rolling boil for at least a minute before drinking, brushing teeth, making juice or washing vegetables that aren't going to be cooked.

It is safe to use the water to shower or wash dishes.

According to the city's website, organisms could be found in the water that could cause cramps, nausea or headaches.

Also, infants, young children, elderly citizens and people with severely compromised immune systems could be at a higher risk if they drink water that is not boiled.

The last time the area east of the Reversing Falls Bridge was under a boil order was in April.

About 35,000 people, excluding people in parts of the neighbourhood of Millidgeville, were affected.

The most recent boil water order was on the city's west side in August.