Drinking water - Frequently asked questions

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Drinking water quality and safety

Where can I find information on Ottawa’s drinking water quality?

The City prepares an annual report for each municipal drinking water system, in compliance with the Safe Drinking Water Act.

Do I need to filter or boil my water?

You do not need to filter or boil your tap water. Be aware of door-to-door sales representatives making false claims about the City’s tap water being unsafe.

Ottawa’s drinking water consistently meets all Federal and Provincial standards. The City of Ottawa publishes an extensive drinking water quality sampling and testing program, and City staff will respond promptly to any concerns or inquiries about drinking water quality.

In some cases, the use of a water treatment device might be justified or could improve the aesthetic quality of your tap water:

  • If you are served by one of Ottawa’s municipal well systems, you may want to consider an in-home treatment device (such as a water softener) for aesthetic reasons.
  • If you have a home with a lead water service pipe or lead in your internal plumbing, you may also want to consider using an in-home filter to remove lead from your tap water.

For more information, please email info-water@ottawa.ca or consult Health Canada’s resources before purchasing an in-home water system.

What if I am on a private well?

For more information on water quality for residents living on a private well, please consult with Ottawa Public Health.

Is the manufacture and sale of water treatment devices currently regulated in Canada?

The manufacture and sale of water treatment devices for home use is not regulated in Canada. However, the National Sanitation Foundation (NSF) in consultation with Health Canada has developed voluntary performance standards for water treatment devices and certification by the NSF is the only guarantee that a device can meet specified performance standards for removal of specific contaminants. For more information visit nsf.org.

Is Ottawa’s drinking water hard or soft?

Water hardness is caused by the presence of calcium and magnesium minerals in water. Ottawa’s water supply is considered very soft due to the natural softness of the source water (Ottawa River). Hard water does not pose any health concerns, however it can lead to scale deposits on hot surfaces such as kettles and hot water tanks.

Ottawa’s central drinking water supply is about 30 mg/L (ppm) of total hardness which is considered very soft. This is equivalent to 2.5 grains per gallon of hardness. In Ottawa’s municipal well systems, hardness levels are much higher due to the presence of calcium and magnesium minerals present in the ground water. Residents may want to install a water softener system to remove hardness minerals for supplies with hardness levels that are moderate or high. It is important to note that sodium levels can be greatly increased after passing through a water softener, which may be a concern for people on sodium restricted diets.

For reference, hardness levels (in mg/L or ppm) are shown below for each of Ottawa’s municipal water systems:

Water system Hardness
Ottawa central water supply 30 mg/L (very soft)
Carp well system 200 mg/L (moderate hardness)
Kings Park (Richmond) well system 350 mg/L (hard water)
Richmond West Well System 285 mg/L (moderate hardness)
Munster well system 285 mg/L (moderate hardness)
Shadow Ridge (Greely) well system 350 mg/L (hard water)
Vars well system 200 mg/L (moderate hardness)

How are drinking water standards set?

In Canada, drinking water is the jurisdiction of each province. Health Canada, through a Federal/Provincial/Territorial committee, establishes national guidelines and maximum acceptable concentrations for certain substances that might occur in drinking water supplies and could have adverse effects on human health.

When a drinking water guideline is proposed or revised, a public consultation process is carried out before final approval.

In Ontario, the Ministry of Environment, Conservation, and Parks (MECP) reviews the Health Canada drinking water guidelines and either adopts or modifies the guideline as an Ontario Drinking Water Standard. In most cases, the provincial standard is identical to the Health Canada guideline; however, in some cases the Province of Ontario adopts a more stringent standard.

Is the City's Medical Officer of Health satisfied with the quality of Ottawa's drinking water?

Yes. The Medical Officer of Health and Ottawa Public Health routinely review the results of the City’s water quality monitoring program, and work collaboratively with Water Services staff to review any concerns or operational emergencies related to drinking water safety.

In the event of suspected or potential risk to the water supply, a public drinking water advisory would be issued by Ottawa Public Health. In most cases, these measures are carried out on a precautionary basis, and are lifted once the water supply is deemed safe.

What is Ottawa doing to further improve the quality of its drinking water?

The City carries out extensive research studies and experiments to better understand our treatment process and to improve drinking water quality for residents. New methods of water treatment are being evaluated at the City’s Pilot Plant Research Facility, located at the Britannia Water Purification Plant. These studies are completed in collaboration with several Canadian universities and North American research agencies.

How can I get my tap water tested?

If you have concerns about the quality of your tap water, and these cannot be resolved over the phone, you can arrange for onsite testing of your water. Contact the City of Ottawa at 3-1-1 to arrange an appointment. There is no cost for this service.

Taste, odour and appearance

Why does my water have an “earthy” or “musty” odour?

Ottawa's water system draws from the Ottawa River, which has a natural, slightly "earthy” or “musty" odour. This odour is caused by trace levels of natural organic substances produced by plants and algae in the river. The water purification process removes most of these substances, but some individuals may still notice an odour, particularly when tap water is warm (e.g. when showering). This odour is not a health concern.

Why is there a “sulphur” or “septic” odour coming from my tap?

If you notice a "septic” or "sulphur" odour when using bathroom and kitchen faucets, it is usually caused by decaying hair, dirt and debris that is caught in the drain. To check this, fill a glass with cold water and take it to another room in the house to smell it. If the water does not have a septic odour, then the problem is likely due to the sink drain.

To correct the problem, you must clean the drain, potentially with the use of a chemical drain-cleaning product. Alternatively, you can pour a small amount of baking soda, followed by vinegar, down the drain. Wait a few minutes and then run your cold-water tap for one minute.

Why does my water look cloudy?

At times during the year, you may find that your tap water appears cloudy. This is not a health concern. This cloudy water is due to the release of excess air bubbles in the tap water. As water travels from the City’s distribution system to your home’s internal plumbing it warms up. Since warm water holds less air than cold water, excess air bubbles may be released when filling a glass, resulting in a cloudy white appearance. The cloudy appearance should disappear within a few minutes. To confirm this, pour some cold water into a glass and observe. You should notice the air bubbles gradually disappear as they rise up from the bottom of the glass within a few minutes.

If the cloudiness persists, call 3-1-1 to arrange for water quality testing.

Why is my water rusty or discoloured?

If the water in your cold water tap or toilet tank is rusty, yellow, or discoloured, this indicates the presence of iron, sometimes found in areas that are supplied by cast iron water mains. This discolouration is usually caused by nearby construction, in areas of low water usage, or where fire hydrant flushing or testing is being conducted. Sudden changes in flow can disturb rust or iron sediment within older water mains. This is a fairly common occurrence and is normally solved by City staff flushing the water main through a hydrant. Please note that these low levels of iron, while not aesthetically pleasing, do not pose a health concern.

If you observe “rusty” water, flush your cold-water taps for several minutes until it runs clear. If the issue persists for more than a few hours, call 3-1-1 to arrange for a site visit. Avoid doing laundry with “rusty” water since it may stain your clothing.

Why are there particles or sediment in my tap water?

On occasion, residents have observed particles in their tap water. Here are a few common reasons why particles might be present:

  • White/brown particles: If the particles are white and appear to have a slight brown appearance on one side, it might be a piece of ceramic from the liner of your hot water tank. To check this, the particle should be able to be crushed with a spoon and should fizz when vinegar is added. Contact your hot water tank supplier and have it inspected if you find ceramic particles in your water.
  • Sand or sediment: If the particles appear to be sand or sediment and are observed in the storage tank at the back of your toilet, it is most likely sediment that was disturbed from the water main. Hydrant flushing will generally clear any sediment from the water mains in your area. If the issues persists, contact 3-1-1 to have the hydrant flushed again.
  • Black particles: Black particles can sometimes be small pieces of rubber from a deteriorating gasket or rubber washer in your tap fixture. In some cases, black particles can be caused by the presence of high levels of manganese in a groundwater well. In this case, contact 3-1-1.
  • Reddish/brown: If you observe tiny brown particles in your tap water, it might be resin beads from a water softener or filtration system. These beads look almost translucent and their presence indicates your water softener needs to be inspected or replaced.

What is the pink stuff in my bathroom?

Many customers report a persistent pink stain in their bathroom, usually on moist surfaces such as tile grout, showerheads, sink drains, or bathtub surfaces. This is usually caused by an airborne bacterium called Serratia marcescens which are commonly found in air, dust, and soil. These bacteria thrive on moisture and dust, especially in areas under construction or near farms. These bacteria are not present in Ottawa’s tap water, but when they colonize from the air, they produce a pinkish or orange film on surfaces that are warm and moist, such as bathroom surfaces. The best solution to keep these surfaces free from the bacterial film is routine cleaning using a disinfectant such as a bleach-based cleanser. Installing a bathroom fan will also help to minimize the moist environment in bathrooms. These pink bacteria do not represent a health concern.

Chlorine and chloramines in drinking water

Why does the City use chlorine and chloramines?

In Ottawa, free chlorine is used as a primary disinfectant during the water purification process to kill bacteria, viruses, and other pathogens. In the final water treatment step, aqueous ammonia is added to react with chlorine and form chloramine, a mild form of chlorine that is commonly used in water distribution systems. Ottawa initiated the use of chloramine in June (1992) to achieve the following benefits:

  1. Chloramine produces much lower levels of disinfection by-products such as trihalomethanes (THM).
  2. Chloramine is more stable and better able to inhibit biological growth throughout the water distribution system.
  3. Chloramine has little or no “chlorine” taste for consumers.

Chloramine is recognized and approved for use in drinking water systems in Ontario and is cited by Health Canada as an effective method for distribution system disinfection. Rigorous testing of Ottawa tap water is conducted regularly by plant operators and field technicians, verified by certified laboratories, and the results are reviewed by the Ministry of Environment, Conservation and Parks (MECP) and Ottawa Public Health to ensure residents have access to a safe water supply.

In Ottawa’s municipal well systems (Carp, Munster, Kings Park, Richmond West, Shadow Ridge, and Vars) free chlorine is added to provide disinfection during treatment and to maintain water quality throughout the distribution system.

What are trihalomethanes (THMs)?

THMs (or trihalomethanes) are a family of trace chemical compounds that form when chlorine reacts with naturally occurring organic material in water. High concentrations of trihalomethanes in drinking water have been associated with certain types of cancer.

Health Canada and the Ontario Ministry of Environment, Conservation and Parks (MECP) have set a standard of 100 µg/L, or parts per billion (ppb), as the safe maximum level of THMs in drinking water, based on a lifetime of consumption.

The City’s water treatment process has been optimized in recent years to lower the concentration of THMs formed during treatment to approximately 35 ppb of THMs on average, which is well within the safe drinking water standard of 100 ppb.

Keeping your tap water lead-free

Is there lead in Ottawa's drinking water supply?

Drinking water supplied by the City is lead-free. However, trace amounts of lead can dissolve into drinking water during contact with your home’s lead pipes (including your water service pipe), brass fixtures, and lead solder. This may impact the safety of your tap water.

In most cases, lead concentrations in Ottawa’s tap water are well below the drinking water standard of 10 ppb (parts per billion), as established by the Province of Ontario. Typical concentrations are as follows:

  • 0 ppb leaving Ottawa’s water treatment plants
  • Less than 1 ppb for tap water in the majority of Ottawa homes (85%)
  • 1-5 ppb in older homes with lead water service pipes

In some homes, the lead concentration can be higher than 10 ppb, usually due to the length of the water service pipe connected to the home.

Please note: Due to increasing concerns about negative health effects in children, Health Canada has established a new maximum allowable concentration for lead in drinking water of 5 ppb. The Province of Ontario is currently reviewing its maximum allowable concentration of 10 ppb and will be implementing a revised Ontario Drinking Water Standard, although the timeline has not been determined.

What is a water service pipe?

A water service pipe connects a building to the City’s municipal water supply. Property owners are responsible for the pipe from their home to the water shut-off valve (referred to as the private portion) and the City owns and maintains the pipe from the water shut-off valve to the watermain (referred to as the public portion).

Who is impacted by lead in drinking water?

Approximately 15% of homes in Ottawa were originally constructed with water service pipes made of lead. Lead pipes were used in home construction up until the 1950s. After that, water service pipes were made of copper. If the original lead water service pipe has not been replaced there is the potential for small amounts of lead to dissolve into household tap water.

Ottawa residents who live in homes built after 1958, as well as commercial and multi-residential properties are at little or no risk of lead exposure through tap water.

Post-1958 homes connected to older watermains

In limited instances, properties built after 1958 may be connected to an older watermain. In this situation, while your private water service pipe (from the water shut-off valve to your home) likely does not contain lead, the City (public) portion of the water service pipe (from the City’s watermain to the water shut-off valve) may contain lead.

To ensure your water service pipe is correctly assessed, we recommend that you call 3-1-1 to inquire about the age of the watermain.

How do I know if I have a lead water service pipe?

The best way to determine if your water service pipe is lead or copper is to scratch the service pipe with sandpaper to expose bare metal. The only visible portion of the water service pipe is located between your basement’s concrete floor and the water meter. Lead pipes are dull grey in colour and are easily scratched by a hard object. Copper pipes are red-brown and corroded portions may show a green deposit.

What is the current limit for lead in drinking water?

Due to increasing concerns about negative health effects in children, Health Canada has established a new maximum allowable concentration for lead in drinking water of 5 parts per billion (ppb). The Province of Ontario is currently reviewing its maximum allowable concentration of 10 ppb and will be implementing a revised Ontario Drinking Water Standard, although the timeline has not been determined.

The maximum allowable concentration of lead in drinking water aims to protect infants, young children and children in-utero who are most at risk of exposure to lead.

Should I be concerned about exposure to lead in drinking water?

Exposure to small amounts of lead is especially harmful for pregnant women and can have harmful effects on a child’s development.

Lead can be present in many environmental sources including soil, dust, food, air, and drinking water. Some household products such as jewellery, crystal, and ceramic pottery can also contain lead. Household dust and dirt often represent the greatest lead exposure for young children.

Although the lead contribution from tap water is generally low, it can be significant in some homes with lead water service pipes.

Visit Health Canada's website for more information on lead and human health, or contact Ottawa Public Health at 613-580-6744 (TTY: 613-580-9656), or by email at healthsante@ottawa.ca.

Is lead a concern in my children’s school or child care centre?

All schools, private schools and child care centres in Ontario are required to flush plumbing regularly, test water for lead annually, and take immediate action if levels exceed the Ontario Drinking Water Quality Standard of 10 ppb. As of July 2017, every drinking water fountain and any tap that provides drinking water or is used to prepare food or drink for children under 18 must be sampled for lead.

Ottawa Public Health ensures that schools, private schools and child care centres resolve lead-related drinking water issues and therefore comply with Ontario Drinking Water Standards. More information is available from the Ontario Ministry of Environment, Conservation, and Parks (MECP).

Who is responsible for replacing water service pipes?

The water service pipe that connects to your home is composed of two portions: a public portion owned by the City from the City’s watermain to the water shut-off valve, and a privately-owned portion from the water shut-off valve to your home. When a water main is replaced or upgraded, the City replaces the public portion of the lead service pipe with copper. Unless the homeowner pays to have their portion of the water service pipe replaced, it will remain as lead.

Is there assistance available to replace a lead water service pipe?

Property owners are encouraged to take advantage of the Lead Pipe Replacement Program.

Are commercial and multi-residential properties impacted?

No. Lead has never been used for larger diameter pipes required for connections to larger buildings, schools, or institutions. Stronger materials such as copper, iron, or plastic are used to supply water to these buildings.

What is the City of Ottawa doing to reduce the risk of exposure to lead?

The City takes the following actions to mitigate the risk of exposure to lead in tap water:

  • The City adjusts the water supply pH to 9.2 – 9.4 to minimize the amount of lead and other metals that can dissolve into tap water.
  • The City routinely monitors tap water lead concentrations in older homes through an extensive water sampling and testing program.
  • Although Ottawa’s water supply meets regulatory standards for lead in drinking water, City staff are evaluating alternative treatment options and strategies to further reduce lead in tap water.
  • The City will test your tap water for lead, free of charge. Call 3-1-1 for this service.

I live in a home with lead plumbing. What should I do to reduce the lead in my tap water?

To minimize lead exposure from tap water, residents are encouraged to:

  • Run their tap for approximately 2 minutes to flush stagnant water sitting in the service pipe prior to cooking or drinking. This can greatly reduce lead concentrations in your tap water. 
    • The cost of water is approximately 2 cents for a two-minute tap flushing.
    • Keep a fresh jug of flushed tap water in the refrigerator for use during the day. Ensure the jug or container itself is lead-free.
  • Request to have your home’s drinking water tested for lead.
  • Use a tap or pitcher-style filter to remove lead from tap water when used for drinking and cooking. Many water filters will sufficiently remove lead from tap water, but the City recommends a filter certified to the NSF/ANSI 53 standard for lead removal. Residents can complete an online search for an NSF-certified filter.
    • Tap faucets and fixtures used for drinking water should be certified to the NSF/ANSI 372 standard as lead-free.
  • Take advantage of the Lead Pipe Replacement Program to help with the replacement of a lead water service pipe.

How can I have my tap water tested for lead?

If you’re concerned about the potential presence of lead in your tap water, you can request a water quality test.

Is there a recommended time of year to have my tap water tested for lead?

Lead testing of tap water can be conducted at any time throughout the year, but testing during the summer months is recommended for the most accurate results. Water temperature at the tap significantly impacts lead testing results. The highest lead concentrations (representing the worst-case for a given property) are typically observed from May to September. Warm water temperatures during this period increase the amount of lead that dissolves from lead service pipes, internal plumbing, and tap fixtures.

During the winter months, the temperature of the Ottawa River, the City’s source water, is close to 0°C, resulting in a temperature of approximately 5-10°C at the tap. As a result, lead concentrations at the tap are quite low and often non-detectable during winter. To be more protective for your health, sampling in the warmer months (May to September) is recommended.

Will my home water filter remove lead from drinking water?

Most pitcher-style filters will reduce lead levels in your tap water to safe levels; however, it is recommended that the filter unit be certified to the NSF/ANSI 53 standard for the removal of lead. This information can be found on the label. You can complete an online search for an NSF-approved filter. It is important to change the filter cartridges as per manufacturer’s recommendations. The use of a reverse osmosis treatment system will remove lead completely.

Will boiling water remove the lead?

No. Boiling your water does not remove lead. If boiled, the lead concentration of the water can actually increase slightly as the water evaporates.

What are other potential sources of lead in my drinking water?

Lead may be present in solder used to join copper pipes as well as in brass used in the faucets and plumbing fixtures in your home. However, lead contributions from brass and lead solder are typically quite low (in the range of 1 ppb or less).

If I have a lead water service pipe, is it safe to wash dishes, clothing and shower?

Yes. Residue on clothing and dishes will not impact your health. Your skin will not absorb lead through bathing or showering. 

Is bottled water lead-free?

Bottled water comes from various sources and is subject to inspection by the Canadian Food Inspection Agency under the Food and Drugs Act. Generally, most brands of bottled water have low or non-detectable concentrations of lead. The lead concentration is typically displayed on the bottle. Specific questions and concerns should be addressed to the company directly.

Will lead in tap water affect my pet?

Lead poisoning in cats and dogs is extremely uncommon, particularly from water. Pets can be harmed by high levels of lead exposure from other sources, most commonly dust from lead paint during household renovations, or hobby-related materials that use lead, such as fishing tackle, stained glass or ceramics. If you are concerned about your pet’s health, contact your veterinarian for more information.

Who do I call if I have questions or concerns about my water quality?

Call 3-1-1 if you require additional information or have questions about keeping your tap water lead-free.

Adding fluoride to drinking water

What is fluoride?

Fluoride is a mineral that occurs naturally in soil and water. Fluoride helps to prevent tooth decay by re-mineralizing cavities when they first begin to form and increasing the resistance of tooth enamel to acids that cause tooth decay.

Is there fluoride in Ottawa’s drinking water?

The City of Ottawa adds fluoride to its drinking water. A fluoride concentration of 0.70 mg/L (ppm) is maintained in accordance with recommended levels by Health Canada.

Fluoride is not added to the water from the municipal well systems operated by the City of Ottawa (Carp, Munster, Kings Park, Richmond West, Shadow Ridge and Vars). However, drinking water from these systems contain naturally occurring fluoride that ranges from 0.10 mg/L to 0.70 mg/L. The table below indicates the fluoride levels for each well system:

Water system Fluoride concentration
Ottawa central water supply 0.70 mg/L
Carp well system 0.55 mg/L
Kings Park (Richmond) well system 0.40 mg/L
Richmond West Well System 0.26 mg/L
Munster well system 0.65 mg/L
Shadow Ridge (Greely) well system 0.05 mg/L
Vars well system 0.15 mg/L

More information about water fluoridation is available through Ottawa Public Health.

Turning water on/off and adjusting your service post

How do I turn my water on and off?

If interior plumbing work needs to be done in a home or building and shutting off the basement valve is not sufficient, the City of Ottawa can turn off the water to the property.

The water shut off and turn on fee is updated annually and can be found at water and sewer bill fees.

Please note: Make these requests at least three hours prior to the scheduled work by calling 3-1-1. Please keep in mind that during periods of high volume, the response time may extend beyond three hours.

If water was turned off due to non-payment of a bill, please contact the City of Ottawa's Revenue Division at 613-580-2444.

How do I adjust my water service post?

A water service post controls water flow to a property and is usually located on the City side of the property line. It allows water to be shut off between the water main and the property. The top of the water service post should be visible and flush with the surrounding area, but seasonal expansion and contraction of the ground may change its height. A water service post will continue to function properly even if it is not flush with the surrounding area.

If your service post needs frequent adjustment, you may be able to do the work yourself, but note the following before doing any work:

  • The property owner(s) is responsible if the water service post or water pipe is damaged while attempting to perform an adjustment on their own.
  • Anyone attempting to adjust the water service post should be in good health and know how to use the required tools.

A demonstration of how to lower a water service post is below. To request a water service post adjustment by City staff please contact 3-1-1.

Place a wood block on top of the post and gently tap it with a small sledgehammer to lower it.

If the post has been high for many years, this method will not work and the post will have to be cut or excavated. In these instances the City will have to perform the work. If you own a new home please contact your builder to make the necessary adjustment.