Drinking Water Quality and Monitoring

York Region provides clean, safe, reliable drinking water to more than one million people. It originates from three sources: Lake Ontario, Lake Simcoe and groundwater wells within York Region.

Approximately 80 per cent of water comes from Lake Ontario via the City of Toronto and the Region of Peel who sell treated water to York Region under long-term water supply contracts. The lake water is pumped north to York Region through large watermains. The Town of Georgina is supplied by two intakes in Lake Simcoe. The remainder of York Region’s needs are supplied by 40 wells scattered throughout the Region. Some of this water is blended with lake water.

Water is distributed to our municipalities through a network of approximately 344 kilometres of water mains. The municipalities then deliver it to users and collect money for both the supply of water and the treatment of wastewater. Some residents get their water from private wells located on their own properties.

Learn where your water comes from

Surface water — Lake Ontario:

• City of Markham
• City of Richmond Hill
• City of Vaughan

Groundwater:

• Township of King (Nobleton, Schomberg, Ansnorveldt)
• Town of Whitchurch-Stouffville (Ballantrae and Musselman’s Lake)
• Town of East Gwillimbury (Mount Albert)

Surface water — Lake Ontario and Groundwater (blended together):

• Town of Aurora
• Town of East Gwillimbury (Holland Landing, Sharon, Queensville)
• Town of Newmarket
• Township of King (King City)
• Town of Whitchurch-Stouffville (Stouffville)

Surface water — Lake Simcoe:

• Town of Georgina (Keswick, Sutton, Lakeshore communities)

York Region uses a disinfectant in water treatment processes in order to ensure that its residents get water that is protected from harmful bacteria and other microorganisms. There are two kinds of disinfectant used, depending on the area (chlorine, or the combination of chlorine and ammonia called chloramine). The dose of either disinfectant maintains "chlorine residual" which safeguards our drinking water. After treatment, water is safe for drinking and other uses.

Chlorine is used to treat the water supply in:

• Ansnorveldt
• Ballantrae and Musselman’s Lake
• Georgina, Sutton and Keswick
• Mount Albert
• Nobleton
• Stouffville

Chloramine is used to treat the water supply in:

• Aurora
• Richmond Hill
• Holland Landing
• King City
• Markham
• Newmarket
• Queensville
• Sharon
• Schomberg
• Vaughan and Kleinburg

Water purchased from the City of Toronto and the Region of Peel – approximately 90 per cent of York Region’s total supply – comes pre-treated with chlorine. The treated water is integrated with the Region’s other supplies and further chlorinated if necessary.

Water from Lake Simcoe undergoes multi-stage treatment at the Keswick and Georgina Water Treatment Plants. At these Water Treatment Plants, an intake pipe extends into the lake to draw water to the plant. Screens are in place to remove debris. Raw lake water is then passed through ultra-fine membranes that remove virtually all contaminants, including viruses.

At the Georgina Water Treatment Plant, the water also passes through ultraviolet light reactors that destroy any remaining bacteria. The water then passes through activated-carbon filter beds that take out taste and odour-causing molecules.

Finally, a chlorine residual is added to protect the water from bacteria that might reside in pipes during its journey to users.

Fish owners and kidney dialysis patients

Fish owners must be careful when using disinfected water because chloramines and chlorine can hurt the sensitive skin of fish, reptiles and amphibians. Chloramines and chlorine should be removed from the water before use in aquariums. There are tablets, drops and filters you can find at pet shops that will remove chlorine from the water.

Kidney dialysis patients must be careful when using chloraminated water. If you are on a dialysis machine, be sure to contact your physician for more information.

Iron in groundwater can cause tap water to be discoloured. Municipal water is treated with a method called iron sequestration. This treatment method keeps iron from accumulating on fixtures. However, when water is heated in a hot water tank, the iron sequestration breaks down. This allows the iron to fall out and build up in the bottom of the tank. It is found more often in tanks with high water temperatures and low water usage.

Draining and flushing the hot water tank regularly will keep iron from accumulating in the home.

Occasionally, discolouration can occur in underground pipes. Watermain swabbing is an important maintenance practice, and is the most common cause of outside sources of discolouration. Staff make every effort to notify home owners in advance of maintenance work in their area. Contact your city of town for instructions on how to respond to these events.

This video shows two methods of watermain cleaning used by the Town of Newmarket to maintain and improve water quality conditions within its water distribution system.

There are a few reasons why your drinking water may have a slight taste or odour, the two most common are caused by sitting water and the time of year.

Sitting Water

Problem: The water has been sitting in the pipes for an extended period of time.

Solution: Open your taps for a few minutes to allow fresh water to enter your plumbing system. If your hot water has a musty odour, the hot water tank may need to be drained and flushed.

Time of Year

Problem: Lake algae can cause your water to have a musty or earthy taste and odour during late summer or early fall. When algae die, they release a harmless organic chemical that gives off a musty or earthy smell.

Solution: Municipal filters remove these problems in most cases but may not remove all mustiness in the case of extreme algae growth. York Region’s municipal water is safe to drink regardless.

The areas most commonly affected by lake algae are:

• Keswick
• Sutton
• Vaughan
• Richmond Hill
• Markham

As an option to improve taste, you may choose to use a home treatment device to filter your tap water. Be sure to use and maintain as directed to keep your water clean and safe.

Sodium is normally found in drinking water. It usually comes from natural sources, road salt, water treatment chemicals and ion-exchange water softening units. It can be a concern for people who:

• Have severe hypertension
• Have congestive heart failure
• Are on a sodium-restricted diet

According to federal guidelines and provincial standards, the objective for sodium is 200 milligrams per litre (mg/L). Anything over 200 mg/L will affect the taste of the water. According to the law, the local Medical Officer of Health must be notified when the sodium in our drinking water is more than 20 mg/L, at which point the officer will notify local physicians. Local physicians will advise patients on sodium-restricted diets.

For more information about sodium in drinking water and your health, please read the Sodium in Drinking Water Fact Sheet.

2024 Q2 Average Amount of Sodium – Milligrams per Litre

*The York Water System receives water from Peel Region and the City of Toronto.

2024 Q2 Average Amount of Iron – Milligrams per Litre

*The York Water System receives water from Peel Region and the City of Toronto.

“Hard” water contains calcium and magnesium carbonate. When water is “hard,” it can be difficult to lather and scale forms in pipes and appliances. Many people choose to install water softeners in their homes to reduce hardness which makes washing easier and prevents mineral buildup.

Can the level of water hardness affect my health?

There are currently no known negative health effects related to water hardness. Water softeners exchange calcium and magnesium with sodium or potassium. If this is a concern, you could consider a separate un-softened supply for cooking and drinking. Also, there are filtration units and treatments that can remove sodium from your drinking water.

Hardness Range – Milligrams per Litre of Calcium Carbonate:

• Soft: 0-60
• Moderately hard: 61-120
• Hard: 121-180
• Very hard: More than 180

Groundwater is usually harder than surface water because it travels slowly through sediments that are rich in calcium and magnesium. These sediments dissolve in the water and make it hard. Surface water in general is less likely to dissolve high concentration of minerals, but the water from Lake Simcoe and Lake Ontario tends to be hard. Therefore, the water in York Region is usually hard or very hard.

To convert to grains per gallon, multiply by 0.058417831.

2024 Q2 Average Hardness — Milligrams per Litre of Calcium Carbonate:

*The York Water System receives water from Peel Region and the City of Toronto.

Fluoride helps prevent tooth decay and naturally exists in groundwater and food. It may also be added to some regional drinking water systems. It is recommended by The Chief Medical Officer of Health for the province of Ontario that the level of fluoride in drinking water be between 0.6 to 0.8 parts per million (ppm). For more information about fluoride in drinking water and your health, please read the Fluoride Information Fact Sheet.

Fluoride levels are regularly monitored for each York Region drinking water system.

York Region does not have any lead water service lines. Any lead found in drinking water supplies would be introduced after water leaves Regional infrastructure, most likely through in-home plumbing.

Lead service lines, lead in drinking water and corrosion control are not typically an issue for the Region and its local municipalities due to the relatively young age of infrastructure.

Health Canada’s guideline for lead identifies a maximum acceptable concentration as 0.005 milligrams per litre (revised in March 2019) and the Ontario Drinking Water Standard has a maximum acceptable concentration as 0.010 milligrams per litre. All 2019 water sample results from York Region storage facilities are well below 0.005 milligrams per litre. York Region is meeting both the current and the more stringent future standards.

The Region started testing for lead back in 1996. Results have consistently been well below the regulatory limit. Based on Ontario Regulation 170/03, Schedule 15.1, the Region tests its storage facilities (water towers and reservoirs) for lead annually. Local municipalities have their own requirements for testing in the local distribution systems.

Where can lead be found?

• Water service lines and plumbing in homes built before the mid-1950s
• Solder used to join pipes together before 1990
• Leaded-brass fixtures, such as faucets and valves

As these items corrode, lead can leach into drinking water.

Apartments and other buildings with more than six units do not have lead pipes, regardless of age. Lead is too soft to handle the pressure needed for these types of buildings.

Lead can affect brain development and behavior in children and can lead to increased blood pressure and kidney problems in adults.  According to York Region Public Health, exposure to lead can pose a risk to everyone’s health, those most at risk include:

• Pregnant women
• Infants (in particular those who are fed formula made from tap water)
• Children under the age of six

Should you have lead plumbing or lead service pipes, York Region Public Health recommends replacing your portion of the lead service pipe.

Learn more about ways to reduce lead exposure in drinking water.

York Region provides high-quality drinking water that is safe, clean and affordable.

From a cost standpoint, bottled water is dramatically more expensive. One litre of municipally supplied tap water costs about $0.001. A litre of bottled water costs about $1.50, plus the cost to dispose of the bottle.  Too often, plastic beverage containers are not recycled, ending up in landfill or the environment, taking hundreds of years to break down

York Region implements a rigorous water quality sampling program to ensure your water is safe to drink and works to identify and correct any situation that poses a threat to the area’s drinking water. York Region will issue either a Boil Water Advisory or Drinking Water Advisory if contamination is found.

For information on Boil Water or Drinking Water Advisories, contact:

York Region's Health Connection

Toll-free 1-800-361-5653 | TTY 1-866-252-9933 for the deaf or hard of hearing

Email: [email protected]