Everything You Need To Know About Impacts On Drinking Water Quality From Forest Fires

Posted on July 29, 2021

Photo credit: Chelsea Richardson. View over Osoyoos Lake, British Columbia. 
Around this time of year, your team at BC’s favorite analytical laboratory (CARO, obviously) fields a lot of questions around the impact of these fires and firefighting activity on the current and future health of their drinking water:

“How do these wildfires impact water quality, both now and for the future?”

“If I draw my drinking water from private wells or surface water, what should I be looking for in terms of water quality indicators, and how can I test for these things?”

Pour yourself a tall glass of water while you consider the following answers to these burning questions. (Hint: Keep your eyes out for a special offer for water testing at the end!)

How do these wildfires impact water quality, both now and for the future?

There are quite a few factors that can lead to water quality being impacted by fires. Changes in the amount and timing of snowmelt, buildup of ash, soil erosion, and fire debris as well as the introduction of chemicals to surface water can all impact the quality of possible drinking water sources.

One of the main catalysts of change in chemical levels of water is caused using fire retardants that are applied to properties, in attempts to prevent fires from spreading. Nitrogen, phosphorous and their salts are the most common and abundant chemicals used in fire retardants in BC. 1 When applied following best practices, these compounds are not immediately harmful to human health and should not impact drinking water quality, other than adding a little bit of color. 2 For more information on the fire retardants/suppressants used in BC, check out this resource:

As a result of runoff and changes in the soil complexion, the levels of these nutrients (Nitrogen and Phosphorous) in surrounding waterbodies can become elevated, creating the perfect environment for algal growth and resulting in algal blooms (the scuzzy green stuff you sometimes see on the surface of the water). These algal blooms produce toxins including mycrocystin, which can harm your liver and nervous system.3

Other immediate water impacts to consider are the physical impacts introduced by soil erosion and ash making their way into waterways, and the chemicals these solids might carry (including PAHs, elevated organic carbon levels, etc.) Although local wildlife may survive the immediate threat of the fire, these lingering physical changes can make it harder for species to recover, killing aquatic life, and vegetation. Species populations such as fish, frogs, and microorganisms have all been shown to be impacted by forest fires, and their impact on the overall health of the ecosystem is significant.4

Photo credit: Chelsea Richardson. View over Osoyoos Lake, British Columbia. 

What to consider when these fires reach urban centers?

In the case of urban fires, the amount of harmful chemicals produced is generally higher than in remote areas, due to chemical reactions with household items, building materials, and other structures. The pipes hooked up to the water supply in the city can melt when exposed to high levels of heat, such as fires. After melting, harmful chemicals from various piping material can be released into water supplies. In the 2017 case of the Tubb wildfire in California, for example, the chemical benzene had leached into the community’s water system after the blaze roared through Santa Rosa, causing long term concerns over the quality of the town’s drinking water.5

The introduction of these chemicals can also have significant financial impacts. When fires burn through large urban areas, such as the case with the Fort McMurray fire in 2016, the overall cost of providing safe and clean drinking water to the community increases. For context — according to CBC, before the fire in 2015, the municipality of Fort McMurray spent approximately one million dollars on water treatment. In 2017, the year after the fire, they had to spend between $500,000 to one million dollars over the base amount designated for water treatment, to help alleviate the impacts of the fires.6

The good news is that your municipal water supply folks are masters of their trade, and undoubtedly already hard at work ensuring minimal to no sustained impact on municipal drinking water sources. Most municipalities have rigorous testing routines in place to ensure that the quality of the water being piped to the local communities is safe to drink. Not all heroes wear capes…

What should private well owners be looking for in terms of water quality indicators?

If you’re on a well to supply water to your home, and the area you live in has been impacted by a wildfire, there are additional precautions that should be taken when returning home. Be on the lookout for physical damage to the wellhead, tank, electrical, and treat the water before consumption.7 To confirm potability water quality testing is also recommended.

The primary water contamination concerns for private wells come from chemicals and microorganisms that can enter a damaged well from a fire. Post-fire water testing should consist of nutrient monitoring, so ammonia, nitrate, sulfate, pH, phosphorous, and turbidity levels, all of which are discussed above. Owners should also consider testing for heavy metals such as arsenic, copper, lead, iron, mercury, and zinc, and for bacterial levels (total coliforms and e.coli in particular), both of which may indicate issues with the well’s structural integrity. If you’re living in an urban municipality, questions about the quality of drinking water should be directed to the local water supplier.

We’ve got you covered.

All of the contaminants listed above can be detected using CARO’s at-home water testing kits (see the Essential Drinking Water Test Kit for a list of parameters). Our kits are easy to access, even easier to use, and can help you assess general drinking water quality as compared to the Canadian Drinking Water Quality Guidelines.

It is our goal to help make testing accessible to all Canadians, so you can make informed decisions about the quality of the water you consume. From now until the end of August 2021, order your water testing kit through CARO’s online store and receive 30% off your order with the code: firewater30.

For more information about testing your water, visit our water testing page here , To order your kit, visit our store here.

Cited References:
Other Resources:


Richmond, British Columbia

#110 – 4011 Viking Way
#250 – 4011 Viking Way (Corporate Office)
Richmond, BC, V6V 2K9, Canada
Phone: (604) 279-1499 Fax: (604) 279-1599
Email: [email protected]
Monday to Friday 8 am to 5 pm.
Saturday 9 am to 4 pm.
After Hours Emergency: 1 (888) 311-8849


Edmonton, Alberta

17225 109 Ave NW
Edmonton, AB, T5S 1H7, Canada
Phone: (780) 489-9100
Email: [email protected]
Monday to Friday 8 am to 5 pm.
After Hours Emergency: 1 (888) 311-8849


Burnaby, British Columbia

#108 – 4475 Wayburne Drive
Burnaby, BC V5G 4X4, Canada
Phone: (604) 279-1499
Email: [email protected]
Monday to Friday 9am to 8pm.
Saturday 11:30am to 8pm.
After Hours Emergency: 1 (888) 311-8849

    Contact Us

    Yes, I would like to receive exclusive emails from CARO.No, I would not like to receive exclusive emails from CARO.


    Kelowna, British Columbia

    #101 – 3677 Highway 97N
    Kelowna, BC, V1X 5C3, Canada
    Phone: (250) 765-9646
    Toll Free: 1 (888) 311-8846 Fax: (250) 765-3893
    Email: [email protected]
    Monday to Friday 8 am to 5 pm.
    Saturday 9 am to 4 pm.
    After Hours Emergency: 1 (888) 311-8849


    Whitehorse, Yukon (Depot)

    BOX 10 33 Levich Drive


    Whitehorse, YT, Y1A0A8, Canada
    Contact Us for Supplies and Deliveries
    Toll Free: 1 (888) 311-8846
    Email: [email protected]
    Monday to Friday 9 am to 5 pm
    This is a depot with our supplies only. Ship samples to the lab.


    Victoria, B.C. (Depot)

    #3-576 Hillside Avenue


    Victoria, V8T 1Y9, BC, Canada
    Contact Us for Supplies and Deliveries
    Toll Free: 1 (888) 311-8846
    Email: [email protected]
    Monday to Friday 7:30 am to 5 pm
    This is a depot with our supplies and flat-rate next day shipping