Canada's nuclear regulator said on Wednesday that demineralized water found leaking from the power plant in Pickering, Ont., poses no threat to human health.

The Canadian Nuclear Safety Commission confirmed the leak on Wednesday, saying that it appears to have been caused by a pump seal failure.

"The radiological risk to the environment and people's heath is negligible," the CNSC said in a statement.

The Ontario Power Generation notified the nuclear regulator late Monday evening that there was a release of about 73,000 litres of demineralized water at the Pickering A nuclear generating station earlier that day.

OPG confirmed the leak Wednesday afternoon, adding that the leak has been stopped and the faulty pump seal is being replaced.

"People are concerned about nuclear power, but this particular incident is normal water with a bit of radiation. It is well below our regulatory and other limits," OPG's Ted Gruetzner told CTV News Channel Wednesday afternoon.

In a statement, the OPG said the leak will have no impact on the quality of drinking water and poses no risk to human health.

Environment Canada and the CNSC are monitoring the situation.

Demineralized water is water completely free of dissolved minerals and not heavy water, which is used to moderate a nuclear reaction.

John Luxat, a radiation expert with McMaster University, says demineralized water is essentially distilled water used to feed steam generators.

"It is not radioactive; it is not going through the reactors. It is actually just going through steam generators to produce steam to drive the turbines," Luxat told CTV News Channel.

"It is used to remove heat from the heavy water going into the generators, but it doesn't at any time go into the reactor."

CTV Toronto's Paul Bliss said the Pickering plant separates the nuclear reactors from operations that do not involve radiation.

"There is a very big difference between what happens on the nuclear side, where the reactor is and the radiation is, and what happens in the non-nuclear side," Bliss said. "I'm told this is from the non-nuclear side."

The water is used to maintain the temperature of a cooling system. The water is taken out of Lake Ontario and has the minerals removed it so it not corrosive to the plant's steel pipes.

The water was discharged back into the lake. The OPG said the water contained trace amounts of tritium that fell far below the regulatory limits.

Pickering, located about 40 kilometres east of Toronto, is home to two functioning CANDU power plants, with a total of six reactors.

Ontario has three nuclear power plants, one in Pickering and another in Darlington. The last plant, in Kincardine, is the second-biggest facility of its kind in the world.