Thousands of Saint John students are being told not to drink the water in their schools.

As of Thursday morning, fountains in Saint John High School have been declared off-limits and students are drinking bottled water instead. But they are not alone.

Recent testing has found elevated levels of lead or copper in 31 of the 35 schools in the city.

"We're sending letters to every parent tonight," says Chris Toole of School District 8. "Schools are also going to be sending voice messages or emails, that sort of thing. By the end of the day tomorrow, everyone should be pretty much aware of what's going on."

The Saint John district is the tenth district to have its water tested. Lead and copper have been detected in other areas too.

"The levels of the lead and copper, although they exceed the Health Canada guideline, they are not at a level that means immediate risk to students and staff," says New Brunswick Education Minister Jody Carr.

Saint John has the largest number of affected schools.

Many of the city's schools are over 50 years old and some are even approaching the century mark. Many of the buildings were built when lead pipe was the standard for water service and plumbing.

However, officials say the age of the schools may not be the only explanation.

"People don't use water fountains as much as they used to, so there may be issues in regard to water sitting and not flowing through," says Toole. "You know, I see people carrying bottled water all the time."

Most schools in the city have lots of experience dealing with bottled water.

"So far, so good," says school Principal Marijke Blok. "We've had to do it in the past because of boil orders that have been citywide. The kids are usually pretty good about it after the first day, you know, not throwing water at one another."

The problem varies from school to school and may be connected to the service pipes, the plumbing inside the building or the water fountains themselves, which means the plans for fixing the water problem in New Brunswick schools will differ from school to school.

With files from CTV Atlantic's Mike Cameron