Daniel Radcliffe had a very scary moment while filming his newest movie.

While discussing his new film "Horns" on TBS's "Conan" on Thursday, the 25-year-old actor revealed that he had a troubling encounter with a highly dangerous glass of water.

"The thing I hadn't been told about," explained Radcliffe when asked about filming "Horns" in British Columbia, "It is very cold in Canada and as a solution to that, because they don't want the water to freeze in the pipes in the trailers overnight, they put antifreeze in it."

"So it's all non-potable water that comes out the tap," he told host Conan O'Brien. "I did not know that, so I drank a full cup of non-potable water, so I guess like half-antifreeze or whatever it would have been."

"That can kill you!" exclaimed horrified O'Brien. "You drank a glass of water mixed with antifreeze!"

"Yeah but I didn't realize," said the actor. "And then I got horrendously ill and didn't know why I had become so ill, and a couple of weeks later I went to drink a glass of water in hair and makeup and they were like, 'WHAT ARE YOU DOING? DON'T' DO THAT, THAT'S CRAZY YOU CAN'T DRINK THAT WATER."

Radcliffe didn't blame anyone for the mishap, but also pointed out that he couldn't have known about the antifreeze in the water practice.

"I just had never seen the signs though," he explained. "I went back and checked my trailer and there weren't signs in it that said 'don't drink this water', but it was just an accident."

O'Brien couldn't help but ask the "Harry Potter" star how sick he had actually gotten during the incident.

"Real sick, like don't drink antifreeze," said Radcliffe, adding that the liquid had given him "a bit of a drippy tummy."

It took Conan a moment to understand what the actor meant by the phrase but soon playfully responded, "A little chutney on the flupney!"

"That is actually a much nicer way of saying what actually happened to me, it was a disgusting," Radcliffe told the late night host. "I was for feverish three days.

"You got through that, you survived. We're all so happy for that," said O'Brien.

We second that!

"Horns" is now available On Demand and on iTunes.