Two pint-sized punks were busted Tuesday for spiking their teacher’s water bottle with rat poison in their fourth-grade Brooklyn classroom, law enforcement sources said.

Veteran teacher Johanna Cherepany took a swig of the tainted water about 12:30 p.m. Monday at PS 315 in Flatbush, the sources said.

A third student who knew what the boys had done told her mother after school, and the student’s mom called the school’s principal to warn the teacher that her water had been poisoned.

Cherepany, 62, rushed to her doctor’s office that afternoon and was treated for nausea and a spike in blood pressure, but was not seriously sickened or injured by the tainted water, the sources said.

She went to the 70th Precinct station house on Tuesday to report what had happened, and the kids, age 9 and 12, were arrested and charged with reckless endangerment, assault and criminal possession of a weapon.

It was not clear if they pulled the dangerous stunt as a prank or had a motive for targeting their teacher.

Sources said the 9 year old – who will turn 10 next week – brought the poison to school and that both boys laced the teacher’s water with the potentially deadly toxin.

It wasn’t clear how much poison they put in the water, but cops found more of the rat poison in the younger boy’s backpack, the sources said.

Sources said the students would also be disciplined by school officials.

A schools spokeswoman would not specify the punishment, but promised “swift and appropriate action” once an internal probe is complete.

“We are greatly relieved that the teacher is recovering and we continue to closely monitor this situation,” spokeswoman Marge Feinberg said.

Mussolini Mombrun, 34, a former substitute teacher at the school who lives nearby, said Wednesday that Cherepany is a good teacher and person.

“She cares about her kids. She gets the job done,” said Mombrun. “I feel bad for her. She is a wonderful person.”

The ex-sub, who was fired from his job, blamed the school’s principal, identified on the Department of Education’s Web site as Judith Ranft.

“It’s chaos in there. The kids are out of control. They don’t listen. They curse. I have complained but the principal does not follow-up with complaints. The kids [involved] don’t get transferred and more chaos happens.”

The school, which has 841 students, is also called the School of Performing Arts. The building also houses PS 152, which is focused on science and technology.

A similar poisoning incident took place earlier this month in England when two 10-year-olds poured a bleach-like liquid into their teacher’s coffee cup when her back was turned.

Emma Place, 39, was about to take a sip of her beverage when she was warned by another student that it was laced with a toxic substance, The Sun newspaper reported.

The plot was hatched by a group of kids who called themselves “The Mafia.”

Additional reporting by Jamie Schram