Cannington Contributing Area Frequently Asked Questions
Q: What’s happening?
A: Lake Simcoe Region Source Protection Authority is working with Durham Region to ensure the long-term sustainability of drinking water in Cannington.
Through routine monitoring of the Cannington municipal wells, Durham Region has observed increasing nitrate levels in the groundwater that supplies the wells. Nitrate is a naturally occurring substance found in soil and water, but can become elevated due to human activity and at high levels it can pose health risks.
Nitrate levels vary between wells. In recent years, Well 8 (one of the most productive wells in Cannington) has shown the highest concentrations, at times exceeding the Ontario Drinking Water Standard. When this occurs, the well is taken out of service until levels decrease.
If nitrate levels continue to rise and the source is not addressed, this well may need to be taken out of service more frequently, and additional wells may be affected over time. This could make it more difficult to reliably meet the community’s needs.
That’s why steps are being proposed now — to reduce nitrate levels and help protect a safe and sustainable drinking water supply for the future.
Q: Does this mean I shouldn’t be drinking the water from my tap?
A: The water from your tap is safe to drink.
Durham Region carefully monitors and manages water quality in the Cannington system, including real-time monitoring at the treatment plant and blending water from multiple wells to keep nitrate levels low. Drinking water supplied to residents typically contains 3 to 4 milligrams per litre of nitrate, which is safely below the Ontario Drinking Water Quality Standard of 10 milligrams per litre.
The concern is for the long-term sustainability of the groundwater that supplies these wells. If nitrate levels continue to rise, there may be fewer options to manage and blend water, and some wells may need to be taken out of service more often. Acting now helps ensure a reliable and safe drinking water supply into the future.
Q: What does this mean for my well?
A: Nitrate levels can vary across the Cannington area, which means not all private wells will be affected.
If you have a private well and are concerned, you can have your water tested. Durham Region Health Department can provide information on testing and next steps.
Contact:
Health Department
The Regional Municipality of Durham
605 Rossland Road East
Whitby, Ontario L1N 6A3
Phone (within regional limits): 311
Fax: 905-666-6214
E-mail: https://forms.durham.ca/Health/Contact-the-Health-Department
Q: Where does the water in Cannington come from?
A: The Cannington Drinking Water System gets its water from underground sources known as groundwater — water stored below the surface in layers of soil and rock called aquifers.
These aquifers supply water to five active municipal wells (soon to be seven), all of which are located in two areas of town: the Arena wellfield (east Cannington) and the Gravel Pit wellfield (west Cannington).
The wells then pump this groundwater to the surface, where it is treated and distributed to homes and businesses.
Q: How is Durham Region ensuring our drinking water is safe?
A: The Region has a robust process in place to make sure that the water distributed to homes and businesses in the area remains safe to drink. It includes real-time monitoring of water entering and exiting the treatment plant, and mixing water from the five (soon to be seven) wells to keep nitrate levels as low as possible.
To address the increasing nitrate level and protect water quality before it enters the treatment plant, the Region and the Source Protection Authority are proposing additional measures including requirements for regular septic system inspections and restrictions on fertilizer-use in the areas believed to be the source of contamination. These measures are intended to protect the long-term sustainability of Cannington’s aquifers and ensure that the community continues to have safe drinking water for years to come.
Q: How much nitrate is in the Cannington drinking water system?
A: Nitrate levels vary across the municipal wells in Cannington but overall have been increasing over time.
The highest levels have been observed in Well 8 (the Arena wellfield). In 2023, nitrate concentrations approached the Ontario Drinking Water Quality Standard, and exceeded the standard in 2024 and 2025. As a result, Well 8 was temporarily taken out of service and continues to be carefully managed based on ongoing monitoring.
Wells in the Gravel Pit wellfield are also showing an upward trend. If this trend continues, nitrate levels in these wells could exceed the drinking water standard in the coming decades.
Q: Why are nitrate levels important?
A: At elevated levels nitrate can affect human health. For this reason, drinking water is regularly tested to ensure levels remain within safe limits.
The Ontario Drinking Water Quality Standard sets a maximum level of 10 milligrams per litre for nitrate. Levels above this can reduce the ability of blood to carry oxygen, particularly in pregnant women and infants. Long-term exposure to high levels of nitrate may also be associated with health risks including certain types of cancers.
In Cannington, treated drinking water is currently well below this standard and safe to drink.
Q: What is the Ontario Drinking Water Quality Standard
A: The Ontario Drinking Water Quality Standard is a science-based, legally binding standard that sets the maximum allowable levels of substance — such as bacteria and chemicals — in drinking water to ensure it is safe to drink.
For nitrate, the standard is 10 milligrams per litre.
Q: Where is the nitrate coming from?
A: Nitrate in the Cannington area is believed to come from a mix of common sources, including commercial fertilizers used on lawns and farm fields, as well as effluent from private septic systems.
Local soil and bedrock conditions also play a role. In this area, soils are relatively shallow and the underlying limestone bedrock is fractured, which allows water — and any dissolved nitrates — to move more easily down into the aquifer that supplies the municipal wells.
Q: What changes are being proposed?
A: Durham Region and the Source Protection Authority have identified the areas where activities on land are most likely to affect groundwater that supplies municipal wells. These areas are called Issue Contributing Areas.
Within these areas, the following measures are being proposed to help protect drinking water:
- Septic system testing every five years in the most vulnerable areas
- Risk Management Plans for properties using fertilizers, outlining best practices to reduce the risk of nitrates entering groundwater
- Fertilizer restrictions in areas closest to the wells (as shown on the attached maps)
These measures are intended to reduce nitrate levels over time and help ensure a safe and reliable drinking water supply for the future.
Q: Why take a stricter approach to fertilizer use?
A: In some cases, fertilizer use in this area is already managed through Risk Management Plans. These are agreements between the Region and property owners that outline best practices (such as proper storage, handling, and application) to help reduce the risk of nitrates entering the groundwater.
While these measures have been in place for several years, nitrate levels have continued to increase. This suggests that additional steps are needed to further protect the drinking water supply over the long term.
Q: Are there other types of fertilizers I can use?
A: The concern in this area is specifically with nitrate. Most fertilizers contain a mix of nutrients —nitrogen (nitrate), phosphorus and potassium — and are labeled with three numbers (for example, 3-2-2 or 3-1-3) that show the proportions of each.
The first number represents nitrogen (nitrate). Products that begin with a ‘0’ do not contain nitrogen and are generally acceptable to use. Examples include:
- 0-10-10 (used to stimulate root growth)
- 0-20-20 (often used for flowers or fruit)
Municipal and household compost is also acceptable.
Q: Who pays for these mitigation measures?
A: Some measures are provided at no cost to residents. For example, septic system inspections are carried out by the Durham Region Health Department and are fully funded by the Region.
Other measures — such as implementing best practices identified in a Risk Management Plan — may be the responsibility of the property owner, depending on the activity and location. These plans are developed in collaboration with the Region to help reduce risks to drinking water.
Q: Why doesn’t Durham Region just drill another well?
A: The Region continues to explore potential new sources of groundwater to support the Cannington system. However, finding a suitable location for a new municipal well is not always straightforward.
A new well must be able to provide reliable and sufficient water volume, while also meeting strict water quality and environmental requirements. To date, no new locations have been identified that meet all these criteria.
Because of this, it is important to protect and manage the existing water supply to ensure it remains safe and reliable over the long term.
Q: Why can’t Well 8 just be taken out of service permanently?
A: While the highest nitrate levels have been observed in Well 8, other wells in the Cannington system are also showing increasing nitrate levels. This means that taking one well out of service would not address the overall trend.
Well 8 also produces a high volume of water and plays an important role in meeting the community’s water needs. Removing it from service would reduce the system’s capacity.
For these reasons, reducing nitrate levels in the groundwater is a more effective long-term solution than relying on fewer wells.
Q: What can I do if I have questions or comments?
A: You are encouraged to share your questions or comments on the proposed changes.
Written comments can be submitted to:
Don Goodyear
Lake Simcoe Region Conservation Authority
E-mail: d.goodyear@lsrca.on.ca
Mail: Lake Simcoe Region Conservation Authority, 120 Bayview Parkway, Newmarket ON L3Y 3W3
Comments will reviewed as part of the consultation process and shared with the Source Protection Committee, which is responsible for recommending updated to the Source Protection Plan. Final approval of any changes is provided by the Ministry of the Environment, Conservation and Parks.
Q: What is source water protection?
A: Source water protection is about protecting drinking waster before it reaches the tap.
Following the Walkerton tragedy in 2000, the Province of Ontario introduced the Clean Water Act and the Source Water Protection program to help safeguard municipal drinking water at its source.
This approach focuses on identifying activities that could affect drinking water quality near municipal wells and putting measures in please to reduce those risks. While this can include managing or restricting certain activities, it’s an important part of Ontario’s multi-barrier approach to ensuring safe and reliable drinking water.