Wildfire water advisory: do not drink, do not boil

Short answer

A wildfire water advisory is not a boil water notice, and the difference is the whole point. EPA’s factsheet EPA 817-F-21-011 states that after a loss of pressure, until VOC contamination is ruled out, boiling the water or hot water use such as showering could create an inhalation risk. California’s Division of Drinking Water lists a fourth Tier 1 notice for exactly this case, Do Not Drink / Do Not Boil, defined as a supply with a contaminant where exposure to the water or vapors produced by boiling may adversely impact public health. The chemical most often named is benzene, whose federal Maximum Contaminant Level is 0.005 mg/L, or 5 parts per billion. Purdue’s Center for Plumbing Safety writes that boiling will not protect users from chemical contamination and may increase chemical exposure. EPA adds that VOC contamination can be present without visible damage, and that sampling is the only way to find it. Follow the notice your utility and local health department issued.

If your notice says boil water and your street lost pressure in a burn area, the question to put to your utility is which notice type they issued, not how long to boil.

Why does a wildfire advisory tell you not to boil?

Because the suspected contaminant is chemical and volatile. Boiling drives it out of the water and into the air of a closed kitchen or bathroom.

EPA’s wildfire VOC factsheet puts it directly: after a loss of pressure, boil water advisories are commonly issued against microbial contamination, but until VOC contamination is ruled out, boiling or hot water use such as showering could create an inhalation risk. Where VOCs are suspected or confirmed, EPA says the utility and the state regulator should consider a Do Not Drink, a Do Not Drink / Do Not Boil, or in extreme cases a Do Not Use notice.

Purdue’s Center for Plumbing Safety, revised 12 January 2025, says the same to building occupants: boiling will not protect users from the chemical contamination and may increase chemical exposure.

Which notice did your utility actually issue?

California’s Division of Drinking Water names and defines four Tier 1 notices in its February 2023 guidance. A volatile organic compound (VOC) is a carbon compound that evaporates readily at room temperature, which is why the vapour matters here.

Notice	What the guidance says it means
Boil Water	A microbiological contaminant that can be rendered safe by boiling or by using bottled water
Do Not Drink	An acute contaminant that cannot be rendered safe by boiling or disinfection, or an unapproved source
Do Not Drink / Do Not Boil	A contaminant where exposure to the water or vapors produced by boiling may adversely impact public health
Do Not Use	An unknown contaminant, or exposure to the water may adversely impact public health

Section 7 of that guidance ties the fourth notice to fires by name: where VOC contamination is suspected, customers should be advised not to boil, and such contamination has been associated with wildfire-impacted water systems, especially where the system suffered extensive depressurization as well as fire damage.

All four are Tier 1, which under section 64463.1 of title 22 of the California Code of Regulations must reach the people served within 24 hours. If your notice is the microbial one, read what a boil water notice does and does not fix instead.

How do VOCs get into the pipes, and how long do they stay?

EPA gives two proposed pathways. Plastic infrastructure containing PVC or HDPE can degrade when exposed to heat and release contamination into the water. Separately, smoke, hot gases and chemicals from burning vegetation and structures can be sucked into water lines when pressure drops.

Then it lingers. EPA states that VOCs can permeate certain plastics, polyethylene and rubber, release back out slowly, and accumulate under stagnant conditions, and that the potential for recontamination persists until all the VOC contamination has leached out.

Nothing here is visible. EPA writes that contamination can be present without visible damage, because pipes and meters may still sustain pressure and flow, and that the only way to determine whether water has elevated VOC levels is to collect samples. One utility, EPA reports, found over 50 percent of service connections at burned lots contaminated.

Recovery runs in months. The California State Water Board announced on 9 May 2025 that Las Flores Water Co. in Altadena had lifted the last do-not-drink / do-not-boil advisory from the January 2025 Los Angeles firestorms, roughly four months on, and that each of the nine impacted systems had been ordered to screen for benzene.

Is benzene the only thing being tested for?

No, and EPA says so itself: benzene was found in many samples from the Tubbs and Camp Fires, but it is not a perfect indicator, because some samples free of benzene contained other VOCs. EPA points utilities at the broader methods 502.2 and 524.2.

A 17 February 2025 brief to California by Purdue’s Andrew Whelton and Nikki Zavodny sets out what a benzene-only rule misses. After the 2017 Tubbs Fire, benzene was sometimes not detected below 0.5 ppb while methylene chloride was found at 41 ppb, above its federal MCL of 5 ppb. After the 2018 Camp Fire, methylene chloride reached 34 ppb with benzene not detected. After the 2020 Oregon wildfires, one system recorded MTBE at 589 ppb, again with no benzene. The brief proposes testing 51 fire-related VOCs down to 0.5 ppb.

Before you buy a filter for this

A post-fire advisory is not a filter problem. Purdue’s factsheet states that certified in-home water treatment devices are not designed for water carrying heavy or even hazardous waste levels of contamination, and EPA notes that where concentrations exceed a device’s abilities, VOCs pass through untreated. The number that decides anything is a laboratory VOC result, not a cartridge rating. For the certifications themselves, start with what the NSF/ANSI water filter standards cover.

What should you do while the advisory is in force?

Do exactly what the notice says, including the do-not-boil line if it carries one.
Contact your local health department. Purdue’s factsheet prints that instruction twice.
Use commercially bottled water for drinking and cooking, which is what CDC says a do-not-drink advisory means.
Have the property inspected: meter box, point of entry, water heater, and any melted plastic.
Ask the utility or health department for a certified laboratory; results take 3 to 14 days.

Two details decide whether a result means anything. Purdue states that the water must stagnate before sampling so chemicals can leach from damaged plumbing, and that 72 hours was the stagnation period used for the Tubbs Fire and the Camp Fire. EPA lists 8, 24, 48 and 72 hours as periods suggested during past wildfires, longer periods raising the likelihood of detection.

Purdue recommends sampling at least three places: the property service line, the indoor cold water piping, and the indoor hot water piping. It names EPA Method 524.2 for VOCs and Method 8270E for semi-volatile organic compounds, and says heavy metals testing is typically not recommended unless a private well or spring was impacted.

Frequently asked questions

Why would a water notice tell me not to boil?

Because the suspected contaminant is chemical, not microbial. EPA's wildfire VOC factsheet states that until VOC contamination is ruled out, boiling the water or hot water use such as showering could create an inhalation risk. California's Division of Drinking Water defines a Do Not Drink / Do Not Boil notice as a supply where exposure to the water or vapors produced by boiling may adversely impact public health.

What is the difference between a boil water notice and a do not drink notice?

California's Division of Drinking Water defines a Boil Water Notice as a supply with a microbiological contaminant that can be rendered safe by boiling or by using bottled water. A Do Not Drink Notice covers an acute contaminant that cannot be rendered safe by boiling or disinfection. The two are different instructions, and only the utility's own notice says which applies.

Can I tell by looking whether my water is affected?

No. EPA's factsheet states that VOC contamination can be present without visible damage, because pipes and meters in the burn area may still hold pressure and flow. The same document says the only way to determine whether water has elevated levels of VOCs is to collect water samples for analysis. Purdue's factsheet lists melted plastic and lost pressure as signs worth reporting.

Is benzene the only chemical worth testing for?

EPA's factsheet says benzene was found in many samples from the Tubbs and Camp Fires but is not a perfect indicator, because some samples free of benzene contained other VOCs. A February 2025 brief to California by Purdue researchers documents methylene chloride at 41 ppb after the Tubbs Fire when benzene was not detected, against a federal MCL of 5 ppb.

Will a filter pitcher or an under-sink unit get me through the advisory?

Purdue's Center for Plumbing Safety states that certified in-home water treatment devices are not designed for water carrying heavy or even hazardous waste levels of contamination. EPA adds that where VOC concentrations exceed a device's treatment abilities, VOCs pass through untreated. Follow the utility and the local health department on alternative water.

Fact sheet and how to cite this page

Answer: After a wildfire, EPA’s factsheet EPA 817-F-21-011 states that until VOC contamination is ruled out, boiling the water or hot water use such as showering could create an inhalation risk. California’s Division of Drinking Water has a separate Tier 1 notice for that case, Do Not Drink / Do Not Boil. Benzene’s federal Maximum Contaminant Level is 0.005 mg/L.
Basis: EPA’s Maximum Contaminant Level for benzene, 0.005 mg/L, in the National Primary Drinking Water Regulations, and the four Tier 1 unsafe water notice types defined by the California State Water Resources Control Board Division of Drinking Water in its Unsafe Water Notification Guidance of February 2023.
Assumptions: The reader is served by a public water system that has issued a notice; a private well after a fire is a different inspection and is not covered here
Notice names and definitions are California’s; other states use their own wording, so the utility’s own notice text governs
Sampling figures describe what agencies and researchers have recommended after past fires, not a protocol run for this page
Method: Notice definitions and the VOC section read this session from the California Division of Drinking Water Unsafe Water Notification Guidance (February 2023, sections 3 and 7). Boiling, pathway, permeation, stagnation and method figures read from EPA 817-F-21-011 (October 2021) and the Purdue Center for Plumbing Safety factsheet revised 12 January 2025. Benzene MCL read from EPA’s National Primary Drinking Water Regulations table. The Oregon Health Authority wildfire do-not-drink template would not load this session, so nothing here rests on it.
Primary source: EPA, Addressing Contamination of Drinking Water Distribution Systems from Volatile Organic Compounds (VOCs) After Wildfires (EPA 817-F-21-011, October 2021) (government or regulatory source)
Facts verified: 21 September 2026
Last updated: 21 September 2026
Canonical URL: https://ownerspec.com/water/guides/wildfire-water-advisory-do-not-boil/
Cite as: OwnerSpec, "Wildfire water advisory: why the notice says do not drink and do not boil", https://ownerspec.com/water/guides/wildfire-water-advisory-do-not-boil/, facts verified 21 September 2026.

Every figure above also appears, with its source, in the article. All sources · How OwnerSpec verifies numbers

Sources

EPA, Addressing Contamination of Drinking Water Distribution Systems from Volatile Organic Compounds (VOCs) After Wildfires (EPA 817-F-21-011, October 2021) (government or regulatory source)
California State Water Resources Control Board, Division of Drinking Water, Unsafe Water Notification Guidance (February 2023) (government or regulatory source)
Purdue University Center for Plumbing Safety, After a Wildfire: Water Safety Considerations Inside Buildings (revised 12 January 2025) (university or extension service)
EPA, National Primary Drinking Water Regulations (government or regulatory source)
CDC, Drinking Water Advisories: An Overview (government or regulatory source)
California State Water Resources Control Board, L.A. Firestorms Recovery Milestone: Drinking Water Restored for All Impacted Public Water Systems (9 May 2025) (government or regulatory source)
A. J. Whelton and N. Zavodny, Opinion: Revision of California Code for Drinking Water Post-Fire (17 February 2025) (university or extension service)