Do this right now
(3 minutes above 6,500 feet elevation). Let it cool before drinking. Stop drinking, cooking with, or brushing teeth with unboiled tap water until then. If you can't boil, use bottled water or disinfect with unscented bleach — see the table below.
A boil water advisory means your water utility has confirmed, or suspects, that bacteria, viruses, or parasites have entered the distribution system — usually from a main break, a treatment plant failure, or a loss of pressure that let contaminated groundwater seep in through a joint or crack. It is not the same as a chemical advisory, and confusing the two matters: boiling kills living organisms, but it does nothing for lead, nitrate, or industrial chemicals, and it can make some of them worse. The rest of this guide walks through exactly what to do, what’s still safe, and what changes for babies, pregnant people, and pets.
What a boil water advisory actually means
A boil water advisory is issued by a public water system, in coordination with the state drinking water program, when something has compromised the barrier between raw water and your tap. According to the CDC and EPA, the triggering event is almost always one of a short list: a broken water main that lets outside water and soil into the pipe network, a sudden loss of system pressure (which can pull contaminated groundwater backward into pipes through tiny gaps), a treatment plant equipment failure, flooding that overwhelms a treatment or storage facility, or a routine sample that comes back positive for coliform bacteria or E. coli.
The advisory exists because utilities cannot instantly confirm the water is safe once one of those events happens, and confirmation testing can take 24 to 48 hours. Rather than wait to find out whether Cryptosporidium, Giardia, E. coli, Salmonella, or another pathogen actually got through, the utility tells everyone downstream to boil first and ask questions later. Most advisories are precautionary — a pressure drop with no confirmed contamination — and are lifted within a day or two once two consecutive clean samples come back. Some are confirmed events, and those can run longer.
The 2022 Jackson, Mississippi crisis is the starkest recent example of how bad this can get: catastrophic treatment plant failures during flooding left the city under a boil water notice for roughly seven weeks and, at the worst point, without any reliable pressure at all. WaterVerge’s coverage of the Jackson crisis is a useful case study in how fast an aging system can go from routine advisory to full emergency.
Most advisories, though, are far less dramatic and far more local: a construction crew hits a water main a few blocks from your house, pressure drops for six hours while crews repair it, and the utility issues a precautionary advisory for the affected pressure zone only — not the whole city. That distinction matters when you’re trying to figure out whether a notice on the local news actually applies to your address. Utilities typically publish advisory boundaries by street or pressure zone on their website or a reverse-911 alert; when in doubt, treat your own tap as affected until you’ve confirmed otherwise.
The three types of advisory — and why the difference matters
Not every “don’t drink the tap water” notice is the same, and the distinction determines whether boiling even helps.
| Advisory | What it means | Does boiling help? |
|---|---|---|
| Boil Water Advisory | Suspected or confirmed microbial contamination (bacteria, viruses, parasites) | Yes — boil 1 min (3 at altitude) |
| Do Not Drink | Chemical contamination — a substance heat can't destroy | No — use bottled water only |
| Do Not Use | Severe chemical contamination — unsafe even for skin contact | No — avoid all contact, use bottled water |
A Boil Water Advisory targets living organisms. Heat kills them, so once the water has been at a rolling boil for the required time, it’s safe to drink, cook with, and use for hygiene.
A Do Not Drink advisory is issued when the contaminant is chemical, not microbial — nitrate from agricultural runoff, a fuel or solvent spill, or a treatment chemical overdose are typical triggers. Boiling does not remove these. In some cases it actively concentrates them, because the water evaporates but the contaminant does not. Utilities issue Do Not Drink notices when boiling would not help, or would make things worse, and direct residents to bottled water for drinking and cooking; bathing and dishwashing restrictions vary by contaminant.
A Do Not Use advisory is the most severe and, per EPA guidance, the rarest. It means the contamination is dangerous even through skin contact or inhalation — not just ingestion — so the instruction is to avoid the water for any purpose, including bathing, laundry, and dishwashing, until the utility confirms it is safe.
Boiling has no effect on lead, nitrate, PFAS, or algal cyanotoxins — and can concentrate them as water evaporates. If your notice says "Do Not Drink" or "Do Not Use," boiling is not the fix. Check the notice type before you reach for the kettle.
How to boil or disinfect water correctly
If you’re under an actual boil water advisory (not a chemical notice), the CDC’s method is simple, but the details matter — a fast boil that never reaches a rolling boil, or a boil cut short, doesn’t reliably kill everything.
| Boiling — sea level to 6,500 ft | Rolling boil, 1 full minute, then cool |
| Boiling — above 6,500 ft elevation | Rolling boil, 3 full minutes, then cool |
| Bleach disinfection — clear water | 8 drops (about ⅛ tsp) unscented 6% bleach per gallon |
| Bleach disinfection — cloudy, murky, or cold water | Double the dose: 16 drops (¼ tsp) per gallon |
| Bleach contact time before use | Stir, then wait at least 30 minutes |
| Bleach type to use | Plain, unscented household bleach only — 5–9% sodium hypochlorite, no added dyes or fragrance |
Filter out visible dirt or sediment first — cloth or a coffee filter through a clean container — before boiling or dosing with bleach; cloudy water shields pathogens from both heat and chlorine, which is exactly why the CDC doubles the bleach dose for it. If you have neither a working stove nor bleach on hand, unopened commercially bottled water is the fallback and needs no treatment.
Bleach disinfection kills bacteria and most viruses effectively but is less reliable against Cryptosporidium, which is why boiling — not bleach — is the CDC’s first-choice method whenever you have a working heat source. Cryptosporidium and Giardia are chlorine-resistant enough that WaterVerge’s waterborne parasites guide covers them as a distinct risk category from bacterial contamination.
A few practical notes that trip people up. Only use plain household bleach — no splash-less formulas, no scented variants, no “outdoor bleach” or color-safe products, since those contain additives not meant for consumption. Check the label’s active ingredient percentage before dosing; the 8-drops-per-gallon figure assumes 5–9% sodium hypochlorite, which covers nearly all US retail bleach, but concentrations occasionally vary and the bottle will state the exact percentage. Boiled or bleach-treated water can taste flat or slightly different — pouring it between two clean containers a few times aerates it and improves the taste without undoing the disinfection. And once water has been properly treated, store it in clean, covered containers; leaving treated water uncovered in an open pot for hours reintroduces the risk you just eliminated.
What’s safe to do — and what to avoid
Most of a boil water advisory is spent making judgment calls about ordinary household tasks. Here’s the breakdown households actually need.
| Activity | Status | Notes |
|---|---|---|
| Showering / bathing (healthy adults) | Generally safe | Avoid swallowing water; keep showers short |
| Handwashing with soap | Safe | Follow with hand sanitizer if hands will touch food |
| Washing dishes — dishwasher hot cycle | Safe | Use a full heated cycle or add a sanitize setting |
| Washing dishes — by hand | Use boiled or bottled water | Tap water alone isn't reliable for hand-washing dishes |
| Drinking straight from the tap | Not safe | Boil first or use bottled water |
| Ice from the freezer's ice maker | Not safe | Discard existing ice; the line feeds from unboiled tap water |
| Brushing teeth | Not safe | Use boiled or bottled water |
| Mixing powdered infant formula | Not safe with raw tap water | See infant guidance below |
| Watering pets from the tap | Not safe | Use boiled and cooled, or bottled, water |
Special guidance by group
Use ready-to-feed formula if it's available — it needs no water. If you must mix powdered formula, boil water and let it sit about 5 minutes to cool slightly, then mix while still hot enough to kill Cronobacter and other bacteria that can contaminate powdered formula itself. Babies under 2 months, premature infants, or those with a weakened immune system need extra care with every bottle during an advisory.
Follow the same boil-or-bottled rule as everyone else, but treat it strictly — don't rely on "it's probably fine." Waterborne parasites and bacterial infections carry higher complication risk during pregnancy, and there's no upside to testing the boundary.
The CDC specifically advises against showering or bathing with unboiled water if you're immunocompromised or have open cuts, wounds, or sores — organisms that a healthy adult's skin barrier shrugs off can cause real infections. Sponge-bathe with boiled or bottled water instead.
Give pets boiled-and-cooled or bottled water, not tap water straight from the bowl refill. Aquarium and pond water for fish should also be boiled or bottled water when refreshing tanks — fish are exposed continuously, not just at a single drink.
After the advisory lifts
The utility declaring the advisory over doesn’t mean every tap in your house is instantly clean — water that sat stagnant in your home’s own pipes, water heater, and appliances during the advisory needs to be cleared out too.
Run every cold-water tap in the house for about 5 minutes, starting with the one closest to where your water line enters.
Run hot taps for a longer stretch — utilities generally recommend around 15 minutes — since the tank holds standing water from before the advisory lifted.
Dump existing ice, then run and discard two to three batches before using ice again; wipe down the bin.
Dispense and discard several cups through the fridge dispenser to clear the line separately from the tap.
Run the dishwasher and washing machine through an empty cycle before their next real load.
Filters and bottled water — what actually protects you
Most countertop pitcher and faucet-mount filters are carbon filters, and standard carbon media is not certified to remove bacteria, viruses, or parasites — it’s built to reduce chlorine taste, sediment, and some organic chemicals, not living organisms. Relying on a standard pitcher filter during a boil water advisory gives a false sense of security. The exception is a filter specifically certified to NSF/ANSI Standard 231 as a “microbiological purifier,” or units built around reverse osmosis or an absolute sub-micron membrane — those can physically block bacteria and protozoa. Check the box or spec sheet before assuming any filter you own qualifies; WaterVerge’s guide to testing your tap water and best water filter pitchers roundup both note which models carry microbiological certifications versus standard carbon-only reduction.
Bottled water sidesteps the question entirely and is the simplest option if you have it on hand — it needs no boiling, no bleach, and no filter caveat, which is why it’s the CDC’s default recommendation for infant formula and for anyone who wants zero ambiguity during an advisory.
Frequently Asked Questions
Is it safe to shower during a boil water advisory?
For most healthy adults, yes — showering and bathing are generally fine as long as you avoid swallowing water. Keep young children from drinking bath water, and if you’re immunocompromised or have open wounds, sponge-bathe with boiled or bottled water instead.
How do I know if my water needs boiling versus bottled water only?
Read the specific advisory language. “Boil Water Advisory” means boiling makes the water safe. “Do Not Drink” or “Do Not Use” means the contamination is chemical, and boiling will not help — use bottled water and follow the notice’s specific restrictions on bathing and other uses.
Can I use a Brita or similar pitcher filter instead of boiling?
No, unless the packaging specifically states it’s certified to NSF/ANSI Standard 231 as a microbiological purifier. Standard carbon pitcher and faucet filters are not rated to remove bacteria, viruses, or parasites and should not be treated as a substitute for boiling during an advisory.
How long do boil water advisories usually last?
Most precautionary advisories, issued after a pressure drop with no confirmed contamination, are lifted within 24 to 72 hours once two consecutive clean samples clear. Advisories tied to a confirmed treatment failure or major infrastructure damage can run much longer — Jackson, Mississippi’s 2022 advisory lasted roughly seven weeks.
Does boiling water remove chlorine, lead, or PFAS?
No. Boiling only kills living microorganisms — it has no effect on lead, nitrate, PFAS, or algal cyanotoxins, and because water evaporates during boiling while dissolved chemicals do not, boiling can actually raise the concentration of a chemical contaminant that’s already present.
Check your city’s water quality
A boil water advisory is a snapshot of an acute event, but it’s also a signal worth following up on — recurring advisories in the same system often point to aging infrastructure or chronic treatment issues. Search your city on WaterVerge to see EPA violation history, contaminant detections, and how your utility compares before the next advisory hits.