The advisory took effect Thursday.
The city says water usage is up with the arrival of summer. Water consumption increases by up to 50 per cent when people use hoses and sprinklers, officials said.
In addition to increasing demands, the city is currently upgrading the water treatment plant in Pierrefonds.
The plant typically performs at capacity during the summer. Construction is underway to modernize the facility.
Officials advise residents to water plants by hand.
The city has posted information on alternatives to using potable water for watering plants, including rainwater recovery here.