Tap Water Quality and Testing

Take Pride in Markham’s Drinking Water

The City of Markham has a world-class Quality Management System for drinking water. Want more information? Read our Quality Management System Policy .

Our tap water meets and exceeds all Ontario health standards and is yours to enjoy! Learn about our water testing, read our water quality reports, and get answers to your questions below.

Water Testing

Markham's tap water meets or exceeds all water quality standards set out by the Ontario Ministry of Environment and Climate Change. We collect and test water samples each day to meet Ontario's Drinking Water Systems Regulation (O.Reg.170/03). The water in our Distribution System is tested for over 120 factors. These include physical, chemical, organic, inorganic and microbiological parameters.

Water samples are taken from green sampling stations that are scattered across the City. We have more than 100 of these stations. Each year, Markham's water also undergoes thousands of health-related tests to ensure quality.

All water samples are tested at an accredited and provincially licensed laboratory. Each sample sent to the lab is documented, tracked, and tested to meet Ontario Regulation 169/03 Standards for water quality.

Quality Management System

The City of Markham owns, operates, and maintains the Markham Distribution System.

Through the City's Quality Management System Policy, we are committed to:

Providing a trusted supply of reliable drinking water for the customer
Meeting legislation and regulations
Ensuring staff are trained and competent to perform their duties
Protecting our drinking water
Providing the resources for continual improvement

Read our most recent quality management documents:

For more information about the Quality Management System, please contact the Supervisor, Continuous Improvement at 905.477.7000 extension 2737.

Yearly Water Quality Report

Markham collects and tests water samples at 107 locations throughout our distribution system. We test for:

Chlorine residual
Bacteria
Trihalomethanes
Haloacetic Acids
Nitrites and nitrates
Lead
Organic compounds
Inorganic compounds

Licensed City staff collect the samples. The samples are analyzed at an accredited and provincially licensed laboratory.

If there are any problems found in the samples, the City reports them to the York Region Medical Officer of Health and the Ministry of Environment, Conservation and Parks (MECP).

The drinking water distributed to Markham residents in 2020 was of high quality. Read the 2023 Annual Water Quality Report (PDF) for complete details.

Annual Water Quality Report

Copies of these or earlier reports are available by calling 905.477.5530. You can also pick them up at the Waterworks Department at 8100 Warden Avenue in Markham.

Quick Links

Ministry Environment

Municipal Drinking Water System

City of Toronto

City of Toronto Water

York Region

Community Lead Testing Program

Before 1953, lead was used as water service line material for residential houses. Houses built after 1953 used copper. Today, many houses also use PVC plastic for water service lines. All known lead service lines in Markham, from the municipal watermain up to the property line, have been replaced.

All municipalities must test drinking water for lead content. The Ontario Drinking Water Standard for lead is 0.010 milligram per litre. Water with lead content below this concentration Standard is not a health hazard.

As required by Ontario Regulation 170-03, Markham began testing residential water samples in December of 2007. By spring of 2011, after 16 rounds of lead water sampling, over 1400 samples were sampled and tested for lead. These samples were taken on a volunteer basis from many locations throughout Markham – especially older locations.

All lead test results were all well below the Ministry of Environment, Conservation and Parks (MECP) Drinking Water Quality Standards for lead. As a result, the MECP granted Markham regulatory relief from community lead sampling in fall of 2011.

Current Status

Markham still takes 20 system lead samples each year. There could be private service lines from property lines to houses that are made of lead or contain lead. Also, the internal plumbing of a building may still contain lead pipes. If you think your home might have lead plumbing, please contact a plumber. If you think you might be connected to a lead service line, contact the Contact Centre at 905.477.5530.

Frequently Asked Questions

How can I check if my home has a lead service?
Locate your water meter, typically found in the basement, and look at the pipe coming up through the basement floor into the bottom of the water meter. Lead is grey, does not echo if you gently strike it, scratches easily and leaves metallic marks when you rub the scratched area against paper.
Do lead pipes exist in Markham and what is the Town doing to replace watermain service pipes?
Markham has a long standing practice (since the 1980s) to replace aging watermains and water service lines. To this date, all known lead service lines, from the municipal watermain up to the property line, have been replaced. However, there may still be private service lines from the property line to the house that are made of lead or contain lead. Similarly, the internal plumbing of the building may also still contain lead pipes and solder containing lead. Residents are encouraged to replace lead service lines and plumbing on their property. Markham is only responsible for service lines up to the property line.
What are the changes to the existing regulation?
The Ontario Ministry of Environment, Conservation and Parks (MECP) has amended the existing regulations that govern the way in which municipalities test and monitor the quality of drinking water (Ontario Water Quality Standards O. Re. 169/03, and the Drinking-Water Systems Regulation O. Reg. 170/03). The Ontario drinking water quality standard for lead is 10 micrograms per litre of water (10 parts per billion). The MECP has also mandated a Community Lead Testing Program for all municipalities.
What can I do to reduce lead in my drinking water?
Most systems do not have lead leaching into the drinking water. However it is a good practice, after water has been standing in plumbing for a long time, overnight or during the day when home occupants are away, to run your taps before drinking water from them. Allow the water to run until it is noticeably cooler and then continue running the water for about five minutes. Save the water you run during this process for plant watering or washing the dishes. If you flush the toilet or have a shower first thing in the morning, this will reduce the amount of time that you’ll need to run the taps. Always use the cold water tap for making beverages and food preparation. Clean the faucet aerators (small screens) regularly.

Related Information

Well Water Testing

If you have a private well and would like to get your water tested, please visit York Region's Safe Water Program for more information.

Toronto Corrosion Control Plan

Water is delivered to Markham through City of Toronto watermains. Toronto has some old neighbourhoods with old water services that contain lead. The water in this service line can absorb some of this lead. In Markham, we do not have lead services and do not have this problem. We know this because we conducted thorough testing in homes and did not find elevated levels of lead.

To fix its problem, Toronto is taking steps to control corrosion. It's corrosion control plan (CCP) includes phosphate dosing. Phosphates coat the pipes, prevent corrosion, and reduce the amount of lead in drinking water.

The use of phosphates will increase in the total phosphorous found in Markham's tap water up to 1 mg/L. Phosphorous is naturally present in food (such as milk, nuts, and beef) and will have No Impact on drinking water quality. Most users won't notice a change to their water.

If you are an Industrial, Commercial, and Institutional (ICI) water user, you may be slightly affected. If you use municipal water for commercial heating or cooling, manufacturing, or other uses, please contact your heating or cooling supplier or process consultant. They will tell you whether you need to make minor adjustments.

Related Information

Water Quality FAQs

Q: Do I need a home water filtration system?
A: No. Markham's water does not require boiling or extra filtration. It is completely the choice of the resident to install these home water filtration systems. These systems are very expensive to install and maintain.

Q: My water tastes or smells odd
A: Please call the Contact Centre at 905.477.7000 or e-mail customerservice@markham.ca. We may send a Waterworks staff member to look into this issue.

Q: Why is the water sometimes discoloured? (Brown or White)
A: When a fire hydrant is opened, a large volume of water is used. This stirs up iron in the watermain. The iron causes water to be brown. When air becomes trapped in the water, it can look cloudy. This can happen when it travels through pressurized water pipelines. Air will stay trapped until it's released from your faucet.

Q: What is the source of water supplied to Markham customers?
A: Markham's water comes from Lake Ontario. It is treated and disinfected through facilities in Toronto and Peel Region.

Q: How safe is our water?
A: Markham's water is safe. It meets the quality standards set by the Ontario Safe Drinking Water Act (SDWA), 2002.

Q: What is the method of disinfection used?
A: Markham's water is chloraminated. Chlorine and small amounts of ammonia are used to destroy pathogens or disease-causing microorganisms.

Q: How is the quality of the water assured? Is the water tested on a regular basis?
A: Water is tested at source treatment facilities on a regular basis. Markham Waterworks also collects and tests water samples to meet standards in the Safe Drinking Water Act. Please see our Markham Annual Water Quality Report.

Q: What is Markham's water hardness scale?
A: Water hardness refers to the level of certain minerals in a water supply. These minerals are usually calcium and magnesium carbonate. Water hardness does not impact health. Markham's water is considered to be "hard." It has about 123 milligrams per litre, or 8.6 Grains per Gallon.

Door-to-Door Sales

Door-to-Door Sales are Illegal! Beware.

Door-to-Door

Sales Private companies may employ salespeople to go door-to-door selling a variety of water–related systems and products, including treatment systems and water heaters. These sales people ask to enter residents’ homes to view or inspect their water systems and offer water quality tests to homeowners.

They may falsely claim that Markham tap water is unsafe in order to sell a water purification system. Markham tap water is tested and safe to drink directly from the tap without further treatment or filtration. There is currently no mandate, from the provincial or federal government, or the City of

Markham, requiring residents to install additional filtration equipment on their water systems.

Only laboratories fully accredited by the Ministry of the Environment and licensed to perform drinking water quality testing are authorized to perform health-based tests on municipal drinking water.

Markham does not engage in any door-to-door water quality testing or sales. If someone comes to your home claiming to be a City employee under these circumstances, please contact us at 905.477.5530, or contact the Ministry of Consumer Services at 1.800.889.9768. Any City employee visiting a residence will carry photo identification.

What to do

Residents are under no obligation to let sales representatives into their homes.

If residents are suspicious of any sales people coming to their door, or if these persons refuse to leave when asked, residents are encouraged to call York Regional Police for assistance at 1.866.876.542. If they pose an immediate threat to your well being then please call 911.

We also encourage residents to report any visits to Markham's Waterworks Department by calling or e-mailing the Contact Centre at 905.477.5530 or customerservice@markham.ca.

Know your right

The Ministry of Consumer Services provides the following tips, in relation to aggressive sales tactics:

Don't sign on the spot. If the salesperson pressures you to sign, insist you need more time to read the contract, including the fine print.
Get it in writing. Ask about rental fees, installation, repair and extra service charges and promises, including warranties, and insist on getting the details in writing.
Ask for identification. Ask for photo ID, the name of the company the salesperson works for, and to keep a copy of any sales material that the salesperson shows you.
Be sure before you buy. Once a water heater is installed in your home, you will have to pay some costs if you change your mind. These costs include the rental payments still due when you terminate, the expenses the rental company incurs to remove the water heater, and charges for unreasonable or excessive wear or use of the water heater.

Under Ontario’s Consumer Protection Act, 2002, you have the right to cancel a contract if:

You change your mind—for any reason—within 10 days of receiving your written copy of the contract.
The business or salesperson with whom you signed the contract has made a false, misleading or deceptive statement. In this case, you can cancel an agreement for up to one year after you sign it. You also have up to one year to cancel if the agreement does not meet all the requirements of Ontario’s Consumer Protection Act.
The contract you sign is not clear or easily understood, or fails to clearly disclose key information you need to know.
You do not have clear information about your rights in the contract itself.

If you have questions or concerns about the supplier of any water system, purchased or rented, call the Ministry of Consumer Services at 1.800.889.9768 or email consumer@ontario.ca.