From the fire itself to the fight against it and the cleanup after it, every stage of a wildfire can impact your tap water—even the smoke…

And you don't have to be near the flames to be affected. Ash from a Colorado fire can land in a Connecticut reservoir, just as a fire in Quebec can affect reservoirs in New York.

Some of the contamination shows up within days, some of it takes months to wash downstream, and some of it can continue to affect our water supply up to eight years after the fire’s been put out… 

Keep reading to discover exactly how wildfires affect tap water both near and far.

• More than half of America's surface water supply starts on forested land, and that land is often the most susceptible to wildfire. 
• When a neighborhood burns, melting plastic water pipes and decreased water pressure can pull more than 50 dangers into every tap on the system.
• Even when a wildfire is hundreds of miles away, your water can still be at risk when the rivers and reservoirs that feed your system are in (or near) its path. 
• A 2025 study found wildfire contamination can continue to wash into water sources for up to eight years after a fire has been contained.
• Clearly Filtered's Affinity® Filtration Technology protects you from up to 386+ dangerous contaminants, including heavy metals, VOCs, and other dangers associated with wildfires.

Rain and snow fall on forested land, run downhill, and fill the rivers and reservoirs that supply more than half of America's surface water, and serve as the main drinking water source for nearly two-thirds of U.S. cities and towns. Rain and snow falling on grassland and brush supply water to much of the rest of the country. Forest, grass, or brush—it can all burn.

And a wildfire can contaminate that water in more ways than most people realize...

When homes burn, the water lines beneath them can lose pressure, and smoke and gases can get pulled into the lines. When plastic pipes and meters melt, they can release chemicals into the water flowing through them. When the first hard rain hits a burn scar—the bare ground a fire leaves behind—ash and mud wash downhill and can turn rivers black with sediment no treatment plant can handle.

But that’s not all… 

When planes drop retardant, runoff can carry heavy metals from the retardant into our water supplies. When utilities treat water with extra chlorine to fight contamination, that same chlorine can react with ash and form dangerous disinfection byproducts (DBPs) of its own. And when smoke drifts hundreds of miles, it can affect water supplies nowhere near the fire.

Some of that contamination reaches your tap within days, some takes months to arrive, and some keeps coming for years.

Your tap water flows from your local utility to your home through miles of underground pipes. And when the ground above those pipes burns, your water is at risk… 

When plastic pipes overheat, they begin to break down and leach chemicals like benzene, toluene, and xylene into the water inside them. 

Guess what the material of choice is for residential pipes (and meters) built or replaced in the last few decades? Plastic. 

And that’s just the beginning…

Eventually, those same plastic water pipes can melt through and break open. That, combined with the thousands of gallons of water firefighters pull from nearby hydrants to fight that same fire, can lead to a major collapse in water pressure...  

Proper water pressure is critical to keeping your water clean, no matter what your pipes are made of. 

After all, that pressure is what pushes water out of your tap. In doing so, it prevents anything from the outside (like bacteria or dirt) from getting inside your pipes and into your water supply…

When pipes break open, water pressure craters. Next thing you know, those same pipes can become a vacuum, sucking in everything around them through every broken line, hole, or crack the system already had. That’s why, during a wildfire, bacteria, ash, soot, smoke, gases, debris, and sometimes even lead and asbestos can flow right to your tap the moment the pressure comes back.

Whether contaminants leach out of overheated plastic or get sucked in with the smoke, many of the dangerous chemicals that can end up in your water are volatile organic compounds (or VOCs)… 

Labs have found more than 50 VOCs in tap water after wildfires, including cancer-linked benzene, methylene chloride, and naphthalene, as well as nerve-damaging toluene and xylene.

In a recent four-year span (from December 2021 to January 2025), wildfires contaminated pipes with dangerous VOCs in three separate states: Louisville, Colorado, after the Marshall Fire. Lahaina and Upper Kula, Hawaii, after the Maui wildfires. And Pacific Palisades, California, after the Palisades fire. There, crews had to turn off roughly 4,800 access points to restore pressure. The city found benzene at 71.3 parts per billion (more than 14x the legal limit), and about 23,000 customers waited up to four months to be able to safely drink their tap water again

In all three cases, the do-not-drink notices reached well past the homes that burned…

If your home is on the same water system as a neighborhood that burned, you're likely served the same water. After the Eaton Fire, Pasadena's “do-not-drink” notices covered about a third of the city's customers, many of whom didn’t lose their homes. 

And like most contaminants, you can't easily see, smell, or taste VOCs, which means contaminated tap water can still look and smell fine.

Even if your neighborhood isn’t directly affected by a wildfire, millions of us are supplied tap water from a river or reservoir that can be in, or near, a fire’s path… 

Much of New York City's tap water comes from the Catskills, about 125 miles away from the city. Some of San Francisco's comes from Hetch Hetchy Reservoir in the Sierra Nevada, roughly 160 miles out. And Los Angeles gets more than two-thirds of its water from forested land in California and Colorado, some of it more than 200 miles away. 

Every one of those mountain ranges and forests can, of course, burn…

A burn scar is scorched, bare ground with nothing growing on it. Pour a bucket of water on a lawn and much of it soaks into the soil. Pour it on a driveway and nearly all of it runs right off. A burn scar turns a whole hillside into, in essence, a driveway, because the fire has baked the ground hard and killed everything that used to soak up water…

So, the next storm or snowmelt sends everything the fire left behind—ash, soot, charred wood, dead vegetation, loose soil, and the burned remains of anything else that was in its path—sliding downhill into whatever river or reservoir sits below.

Colorado has watched burn-scar runoff hit the same river twice… 

In July 2012, a month after the High Park Fire, heavy rain turned the Cache la Poudre River pitch black with soot and ash, and Fort Collins and Greeley both had to shut off their river intakes and use alternative sources for drinking water. Then the Cameron Peak Fire burned more than 200,000 acres of the same watershed in 2020, and the runoff from that burn scar hit the river the following summer. Greeley, which normally gets about 45% of its water from the Poudre, went about 40 days unable to treat river water at all. 

The city's director of Water and Sewer Utilities called it “too black” and “too [full of] sediment” to bring in and treat. Customers in both cities never noticed, because their utilities had reservoirs to fall back on. Not every city has the same luxury. 

Runoff can carry fire retardant into our water supplies as well…

Retardant is the pink slurry you see planes dropping on hillsides during a wildfire. It's designed to coat vegetation and slow the flames. Crews drop millions of gallons of it during a bad fire season, often on the same slopes that drain into a city's water supply.

A 2024 study at the University of Southern California found one of the most common aerial retardants carries heavy metals at levels that would classify it as hazardous waste according to federal and CA regulations…

Researchers are careful to say they haven't yet drawn a direct line from retardant drops to metals in rivers, but unexplained spikes in metals after fires are what led them to look.

Once that runoff, ash, and retardant reach the treatment plant, the utility has to make it meet federal water safety standards before it is sent to your tap. That’s when treatment can introduce new dangers of its own… 

After all, one of the most common ways to treat contaminated water is with chlorine. Well, ash is rich in organic carbon, and when chlorine meets organic carbon, it can form disinfection byproducts (DBPs) linked to cancer and reproductive harm. 

In other words, the chlorine used to fight the contamination can actually create new contaminants. 

A review in Environmental Pollution found wildfire ash is especially reactive at forming a dangerous class of nitrogen-based byproducts, and that fire can raise the levels of other chemicals that feed byproduct formation. 

How long does a burned hillside keep sending ash and sediment downstream?

In June 2025, researchers at the University of Colorado Boulder analyzed more than 500 western watersheds, burned and unburned, over decades of water records, so they could separate what the fire did from what the weather did. The results showed contaminants like organic carbon, phosphorus, nitrogen, and sediment can degrade water quality for up to eight years after a fire.

That means a fire that made headlines in 2018 could still be affecting your water in 2026… 

For example, after the 1996 Buffalo Creek and 2002 Hayman fires, Denver Water spent millions dredging fire sediment out of Cheesman and Strontia Springs reservoirs. And yet, as of 2026, Strontia Springs is still 10% full of sediment from past fires. 

"Wildfire really is the number one threat to our watershed health," says Aurora Water resource specialist, Matt Ashley.

Here's what a wildfire can leave in your water, where it comes from, and why it matters:

• Benzene, toluene, and xylene. These are industrial solvents, the same chemicals found in gasoline, paint thinner, and the plastics that burn in a house fire. Overheated plastic water pipes leach these dangers into the water, and smoke carries them into water pipes that have lost pressure. Benzene is linked to cancer, and toluene and xylene can damage the nervous system.
• Methylene chloride (Dichloromethane) and naphthalene. Methylene chloride is the active ingredient in paint stripper, and naphthalene is the chemical that gives mothballs their smell. Overheated plastic water pipes can leach both into water, and both have been linked to cancer.
• Lead and asbestos. Burned homes can release both, and water pipes that have lost pressure can then pull them in. Lead can permanently lower a child's IQ, and asbestos is linked to lung cancer, among other things.
• Chromium-6, cadmium, and vanadium. Chromium-6 is the "Erin Brockovich" chemical, cadmium is used in batteries, and vanadium is a steel-hardening metal. Retardant carries all three, and runoff washes them off hillsides into rivers and reservoirs. They’ve been linked to cancer and kidney damage.
• Nitrate and ammonia. The same nitrogen compounds in fertilizer, nitrate and ammonia can be released when vegetation burns. Ash and burn-scar runoff can then carry both into water sources.
• Trihalomethanes (THMs) and haloacetic acids (HAA5). The extra chlorine a utility may add to protect your water can react with ash to form these dangers. They've been linked to cancer and reproductive harm.
• Algae toxins. Smoke-borne ash feeds the algae that make these poisons in reservoirs. The most common one, microcystin, can damage the liver.

A fire in the Rockies reached taps in Greeley, Colorado, a year later. A fire in Quebec settled on reservoirs in New York within days…

And if you were in Chicago in July of 2026, you would remember the sky, as Canadian wildfire smoke pushed the city's air quality to 753, the worst reading in the world that day and the worst Chicago had recorded since regular monitoring began nearly 30 years ago. Beaches closed. Games were postponed. It was the third summer in four years the smoke from wildfires in Canada had settled over the Midwest.

Smoke is ash in the air, and eventually what goes up comes down. When it lands on a reservoir, it brings phosphorus and nitrogen with it, the same nutrients in the fertilizer you spread on your lawn. Then algae feed on those nutrients, and the lake blooms.

In fact, a January 2026 study by EPA scientists tracked more than 2,000 U.S. lakes and found algae rose within two weeks of smoke passing overhead. 

But what’s a blooming lake have to do with your water quality? 

Some blooms produce toxins, and a big enough bloom can overwhelm a treatment plant. For instance, in 2014, a bloom in Lake Erie put about 400,000 people under a do-not-drink notice for two days. 

After a wildfire, your utility tells you what kind of problem it has by which notice it sends…

A boil-water notice typically means bacteria got in, and heat will kill them. A do-not-drink notice typically means chemicals got in, and heat won't help. A do-not-boil notice typically means the chemicals are the kind that turn to vapor, so boiling is not an option. In the worst cases, a do-not-use notice means you must stop using the water for drinking, cooking, making ice, brushing teeth, and so on. 

When a notice lifts, that means the water has tested below the legal limit for whatever dangers the utility tested for. 

This is where things get hairy…

First, legal isn't the same as contaminant-free. For benzene, the chemical utilities tend to test for most often after a wildfire, the federal legal limit is 5 parts per billion (ppb). That means up to 5ppb of the chemical can legally remain in your water. But the health goal, which is the level at which scientists say there's no known risk, is 0ppb. 

See the issue? 

Sadly, benzene is just one of several contaminants that are legally allowed in our water up to a certain level, despite having a health goal of zero. 

On top of that, the water pipes that serve your home can recontaminate your water after a notice has been lifted... 

Once contaminated water has been pulled through a system, water pipe walls can soak it up regardless of what material they’re made from. Then those same pipes can release it back into the water passing through later.

Put differently, water pipes can recontaminate the water that flows through them by leaching contaminants they have previously absorbed.

When a water utility issues any sort of notice, you should always follow their instructions. But don’t make the mistake of assuming your water is contaminant-free just because there’s no active notice. 

Fire or not, the EPA only regulates about 90 of the 324+ dangers detected in U.S. tap water. And like we said earlier, even regulated contaminants can still be dangerous since legal doesn't necessarily mean contaminant-free… 

Meanwhile, ordinary store-bought water filters protect you from as few as 5 of those dangers, allowing hundreds of others to slip through—including many of the odorless, invisible dangers associated with wildfires. 

Our advanced Affinity® Filtration Technology, on the other hand, protects you from up to 73x more dangers than they do, including VOCs, heavy metals, and DBPs. And unlike others, we do it without removing healthy minerals from your water.

That’s why, whether it’s fire season or not, 325,000+ families trust us to protect them. Tap here to upgrade to Clearly Filtered, so you can trust every drop. 

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