Lake Ontario via Metropolitan Toronto and York Region Water Supply System.

All Markham sanitary sewage effluent is discharged via York Durham Trunk System to the Duffins Sewage Treatment Plant in Pickering. The processed and treated sewage effluent is then discharged to Lake Ontario.

The water supply to all Markham residents is safe and meets the quality standards within the parameters as established by the ONTARIO DRINKING WATER OBJECTIVES of the Ontario Ministry of Environment and Energy.

YES - the raw Lake Ontario and treated water is tested by Metropolitan Toronto on a regular basis. Markham Waterworks collects and tests existing water system samples on a weekly basis. All new watermains are tested prior to coming into the existing water system supply.

When a hydrant is opened, there is a large volume of water used, therefore, stirring up the iron in the water main which causes the water to be brown in colour. The water is milky when air is trapped in the system. In either condition, the water is still safe to drink.

This is your water shut-off valve (also called a curb box). Please keep this valve accessible at all times. This will ensure that in the event of an emergency or for major plumbing work in your home, the water to your home can be turned off.