How Wildfires Affect Drinking Water

What happens during the fire, after the first rain, and throughout recovery

A wildfire’s damage to drinking water rarely ends when the fire does. Contamination and damaged infrastructure can leave a community’s water compromised for weeks, months, and sometimes years after the flames are out. I learned exactly how true that is during  the Camp Fire in November 2018. A good friend lived near Paradise, California, and had family throughout the area. After the fire, she was helping the community get back on its feet when she called with a question that sounded simple: What could people trust about their water?

That question led me to speak with the Paradise Irrigation District and to study how wildfires affect drinking water. Specifically, I wanted to understand what happens when intense fire, damaged plumbing, pressure loss, and a long recovery all collide.

The most important rule: If your water provider issues an advisory, follow it exactly. Water that looks clear or has no noticeable odor is not proof that it is safe.

Wildfire-related water problems do not all begin in the same place. Some start in the watershed. After vegetation burns, rain can move ash, sediment, nutrients, metals, debris, and other pollutants into streams, reservoirs, and lakes. The U.S. Geological Survey notes that the effects vary widely, from little noticeable change in some watersheds to major increases in sediment and other constituents in others.

Other problems begin inside the drinking water distribution system itself. The 2017 Tubbs Fire and 2018 Camp Fire showed that hazardous volatile organic compounds, or VOCs, could be found in the distribution network even when the source water was not the origin of that contamination. Research published in AWWA Water Science identified damaged plastic components, heat-driven chemical release, and system depressurization as possible contributors, while also emphasizing that the exact contamination mechanisms were not fully resolved.

Every fire and every water system is different. Still, a four-phase framework helps explain why the risk changes over time and why recovery is rarely as simple as turning the water back on.

Phase One: During the Fire

During a severe fire, heat can damage or completely melt service lines, meters, water mains, pumps, seals, gaskets, storage facilities, and other system components. At the same time, firefighters may draw large volumes of water from different parts of the network. Broken lines and heavy demand can cause pressure to fall or even create negative pressure in parts of the system.

When pressure is lost, cracks and open service lines can become entry points for water contamination. Smoke, gases, contaminated water, and material from burning structures or vehicles may be pulled into the network. Heat can also damage plastic components and may release chemicals directly inside the system. Once contamination enters, normal water movement and emergency repressurization can carry it beyond the visibly burned area.

Phase Two: The Immediate Aftermath

The first days and months after a fire bring a different challenge. Rain can wash ash, sediment, nutrients, and organic matter from burned land into surface water. This can raise turbidity, the cloudiness caused by suspended particles, and complicate treatment. Under some conditions, nutrient and organic loading can also promote algal growth, reduce oxygen, and stress aquatic life.

For drinking-water utilities, the challenge extends beyond visible sediment. Wildfire-related organic matter can increase precursors that form disinfection byproducts, including total trihalomethanes (TTHMs) and haloacetic acids (HAA5), during treatment. Separately, pressure loss or heat-damaged materials may introduce VOCs into distribution systems. EPA-supported research has examined how wildfire, post-fire sedimentation, and organic matter affect turbidity and disinfection byproduct formation during treatment. Because chemical contamination may not be apparent by sight, taste, or smell, and some VOCs can enter the air during hot-water use, always follow the water provider’s advisory.

Phase Three: Intermediate Recovery

Repressurizing a damaged network is a deliberate process. Operators assess damage, isolate badly affected areas, close service lines where possible, repair leaks, flush water, allow lines to stabilize, sample, and test. If contamination is found, the cycle may need to be repeated. Larger systems may recover zone by zone instead of all at once. 

Paradise made the difficulty of this work very real to me. A system can hold pressure only after enough leaks are found and repaired, yet pressurizing the system is often how crews discover the next leak. Each repair may reveal another. Even after pressure is restored, flushing and testing must show that water meets the applicable requirements before restrictions can be lifted.  In some cases a community is able to isolate and repair the cracks or leaking areas quickly. However, in cases such as Paradise, it took them several months to get the system back up and operational due to the severe damage that occurred.

Phase Four: Long-Term Stabilization

Watersheds and distribution systems do not recover on the same schedule. Chemical concentrations may decline while fine sediment continues to move through reservoirs and streams. Distribution lines thought to be intact may fail after everything was thought to be repaired. Rainfall can trigger new runoff events, and treatment plants may face changing source-water conditions long after the fire is out.

That is why recovery should be understood as a monitored process, not a date on the calendar. The duration depends on burn severity, watershed conditions, infrastructure damage, weather, system design, and the results of repeated testing.

What’s the Difference Between a Boil Water Notice and a Do Not Use Order?

A boil water notice generally addresses microbial concerns and tells customers to boil water before drinking or cooking. But boiling does not remove VOCs. Under some chemical-contamination advisories, boiling may be specifically prohibited because heating water could increase inhalation exposure.

California’s State Water Resources Control Board distinguishes among boil water, do not drink, do not drink and do not boil, and do not use notices. The permitted uses vary. A do not use notice is the most restrictive: the water should not be used for any purpose. Other jurisdictions may use different wording, so the controlling instruction is always the notice issued by your local water provider or public health authority. Remember, the exact words used in a water advisory matter.

Do not rely on your senses. Chemical contamination may not be obvious by sight, taste, or smell. Clear-looking water can still be under an advisory.

Check the current notice before using water. Power or pressure returning does not mean an advisory has ended, and restrictions may be lifted one zone at a time. Check your water provider frequently for updates.

Use only approved water sources. Follow local instructions for bottled water or community filling stations, and never use a filter as a substitute for an active water-quality notice.

Ask before flushing. Do not flush while an advisory is active unless the water provider directs you to do so. After it is lifted, follow the provider’s instructions for which fixtures to flush, in what order, and for how long—especially if VOCs or heat-damaged plumbing are a concern.

Inspect and service treatment equipment. After officials clear the water, follow the manufacturer’s instructions before returning a device to service. Sanitation or replacement of activated carbon or other media may be necessary, depending on the equipment and its exposure. If contaminated water reaches the system, contact the manufacturer or a qualified professional.

Test when circumstances call for it. Standard packages may omit wildfire-related contaminants. Tell the laboratory the property was affected by fire and ask which analyses, containers, preservation steps, and holding times apply. Depending on local conditions, testing may include bacteria, VOCs, semi-volatile organic compounds, metals, nitrate, residual disinfectants, and disinfection byproducts. EPA recommends a state-certified drinking-water laboratory. NTL/WaterCheck and Pace Analytical offer relevant services; confirm that the laboratory is certified in your state for the requested analytes and methods.

If you use a private well. Contact your local health department, state environmental agency, or licensed well contractor for guidance. If the well lost pressure, components were exposed to heat, equipment or piping was damaged, or nearby fire damage was severe, do not drink the water until the system has been evaluated and appropriately tested. Have a septic system inspected if it shows signs of heat, structural, or vehicle damage. The CDC’s guidance on private wells after a wildfire is a good starting point.

After the 2023 Maui wildfires, temporary housing and community support sites needed reliable access to drinking water while recovery continued. Honest Water donated several Diamond Silver systems that were connected to filling stations where displaced residents could fill five-gallon containers at no charge. The installations were placed in locations outside the areas directly subject to the most restrictive wildfire water notices.

Testing of the incoming water at these locations did not detect benzene or toluene, two indicator VOCs often monitored after wildfires. It did, however, identify elevated chlorine levels and the elevated levels of disinfection byproducts. After treatment through the Diamond Silver systems, the disinfection byproducts found in the incoming water were not detected above the laboratory’s reporting limits in the post-filtration samples. Repeated follow-up testing over several months produced the same post-filtration results. Those results describe these specific installations, samples, and conditions; they should not be generalized to every wildfire, water source, or treatment system.

The larger lesson was not that one filter solves every wildfire problem. It was that recovery requires coordination: utilities restoring infrastructure, public agencies issuing clear guidance, laboratories verifying water quality, and qualified treatment professionals applying the right technology only after the risks and intended use are understood.

A wildfire can change drinking water in ways that are immediate, delayed, visible, or impossible to detect without testing. It can damage the network beneath a community, send ash and sediment into source waters, increase treatment challenges, and leave operators with months of repair, flushing, sampling, and communication.

For homeowners, the safest response is also the simplest: follow the local advisory, use only approved water sources, and do not assume clear water is safe water. For plumbers and water treatment professionals, the responsibility is equally clear. Understand the notice, verify the water condition, protect the customer’s plumbing, and recommend treatment only when the application and performance are supportable.

The flames may be gone. The work of restoring confidence in the water may just be beginning.

Need help returning a filtration system to service after a wildfire? Contact Honest Water Filter or an authorized Honest dealer for product-specific inspection, sanitation, and filter-replacement guidance. Always follow active instructions from your water provider first.