The move follows a coroners' reports showing that since 2000, 24 seniors in the province have died after having been scalded by hot water.
Willard Wilson, 94, died after falling into a bathtub in a provincally-run seniors residence on Montreal's West Island in January 2009.
He was found by staff, severely burned and in a lot of pain. He died six days later in hospital.
The water temperature that killed Wilson was nearly 60 C.
Wilson's son Eric has been fighting for change ever since.
"What happened to my father should not have happened to him and it should not happen to your father or your mother. It shouldn't happen to anybody," said Wilson.
Wilson said he is pleased with the government's decision to enforce a temperature cap.
"My father's death won't be in vain," he said.
In 2005, the province's Construction Code set a limit of 49 C for the water temperature coming out of faucets, but the rule only applied to new plumbing installations.
Under the new regulations, which come into effect February 11th, facilities must install a temperature-controlling device on taps.
In places where the devices are already installed, the change will have to be made within 45 days.
The government is not requiring the temperature of water stored in hot water tanks to be lowered, because of concerns about bacteria.