Water main break — quick playbook

Page Action Block

  • Do this first: Walk to your house's main shutoff valve (usually inside near the front foundation wall, or at the curb stop in a covered box) and close it clockwise. Stops a flooded basement before you do anything else.
  • Time required: 15 min stabilize → 72 hr maintenance
  • Cost: free (using on-hand storage) to moderate (purchasing bulk water mid-incident if reserves are thin)
  • Skill level: beginner
  • Tools needed: A water-main key or T-handle wrench (for curb stop), a flashlight, your stored drinking water, food-grade containers for graywater, paper plates / disposable utensils (optional)
  • Safety warnings: Boil-water notices are common after mains breaks — most U.S. and Canadian utilities issue a precautionary advisory whenever positive pressure is lost at the repair site (AWWA C651-23). Do not drink any tap water that runs out of the line for the next 24 hours after pressure returns until the utility clears it. Backsiphonage during a pressure drop can pull contaminants into your home plumbing.
  • Legal / regional caveats: Water-utility responsibility for a break depends on the location of the failure (utility-side vs. homeowner-side, divided at the curb stop). U.S. and Canadian municipalities differ; check your utility's terms-of-service.
  • Last reviewed: 2026-05-19
  • Source hierarchy: EPA Emergency Disinfection of Drinking Water (Tier 1), CDC Making Water Safe in an Emergency (Tier 1), AWWA C651-23 Disinfecting Water Mains (Tier 1).
  • Next 3 links: Water rationing during emergencies, Finding water — decision guide, Boiling water for safety.

Trigger and pre-conditions

The precipitating event is a confirmed water main failure: municipal pressure has dropped to zero at every fixture, or you've spotted water bubbling up through the street or your yard. This playbook assumes you are connected to a municipal water system (not on a well), that there is no immediate alternate source plumbed into the house, and that your household has at least the standard 1 gallon (3.8 L) per person per day of stored water — even if only for a single day. The 72-hour outcome this playbook delivers: safe drinking water for everyone in the house, basic hygiene maintained, dishes and cooking continued without sickness, and zero plumbing damage when service is restored.

T+0 to T+15 minutes — Stabilize

Water main break — 72-hour decision tree

Goal: Stop any flooding inside or outside the house, confirm what broke, and tell the utility.

  1. Shut off your house main. The valve is usually inside near the front foundation wall in cold climates, in a crawlspace or garage in warm climates, or at the curb stop in a covered box at the property line. Turn clockwise until firm. This stops backsiphonage (contaminated water being pulled into your plumbing as utility pressure drops) and prevents the line from refilling unannounced into an empty pipe and bursting weak joints.
  2. Open one cold tap on the lowest level (basement laundry, basement bathroom). This relieves residual line pressure and lets you confirm the shutoff worked — water should taper to a trickle then stop within 30 seconds.
  3. Find the break. Walk the street and yard. A utility-side break shows as bubbling pavement, a sinkhole, or a visible plume in the street. A homeowner-side break (between the curb stop and your house) shows as a soft, wet spot in the yard, sometimes with grass dying in a line, or as water in the basement near the service entry.
  4. Call the water utility's emergency line (not 911 unless there's a flood emergency or sinkhole-as-traffic-hazard). Give them the address and the visible symptoms. They will dispatch a crew and may issue a boil-water notice for the affected pressure zone.
  5. Tell your household one sentence. "The water main is broken; I've shut off the house; we have [N] gallons of stored water; we'll talk about the plan in 15 minutes." Avoid alarming children. Do not start running taps to "fill up" — see step 1, the system is unsafe.

Decision criteria:

  • IF the break is homeowner-side (your responsibility, between curb stop and house) → you'll need a plumber and the timeline may be days, not hours. Skip ahead to the T+1 to T+6 hour planning now.
  • IF water is actively pooling in a finished basement → also call your homeowner's insurance line and start documenting damage with phone photos. See threats/post-disaster-recovery.md § Mold remediation 48-hour window.

Failure modes:

  • Shutoff valve seized: Older valves seize from disuse. Don't force a stubborn valve to the point of snapping — call the utility to shut off at the curb stop instead.
  • No accessible curb stop: Some properties have buried or paved-over curb stops. The utility owns this access and will dig if needed; document this for next time and install a riser after the incident.
  • Pressure returns unexpectedly: A neighbor's repair, an automatic system action, or a partial break sealing itself can restore pressure with no notice. If you opened a low tap in step 2 and left it open, you'll know first — but do not drink that water until the boil-water notice is cleared.

T+15 minutes to T+1 hour — Triage and contain

Goal: Know your water budget for the next 72 hours, separate potable from non-potable use, and confirm who in the household has elevated needs.

  1. Inventory your stored water. Count sealed bottled water (count bottles, multiply by ounces or mL), unsealed bottled water (older than 6 months — use for non-potable only), any water rotation drums or carboys, the water heater (40–80 gal / 150–300 L is typical, fully drinkable if you bypass the supply line — see water/storage.md § Water heater bypass), and ice in the freezer (melt-water is potable if the freezer was running normally before the break).
  2. Calculate your budget. Use 1 gal (3.8 L) per person per day as the planning floor for drinking, cooking, and hand-rinsing combined. A household of four for 72 hours needs 12 gal (45 L) at the floor; comfortable level is 1.5–2 gal (5.7–7.6 L) per person per day. If your inventory is less than the floor, you must source more in the next 6 hours — see T+1 to T+6 below.
  3. Separate potable from non-potable. Set out two labeled containers in the kitchen: one for drinking and cooking (anything that touches a mouth), one for non-potable (toilet flushing, dish-rinse first-pass, hand-washing where soap is followed by a sanitizing wipe). Use sealed bottled water and water heater contents for potable. Save unsealed older water, partially-rotated containers, and rainwater for non-potable.
  4. Identify elevated-need members. Anyone in the house on dialysis, with chronic kidney disease, infants under 12 months, pregnant or nursing parents, or anyone with active diarrhea or vomiting needs above-floor allocation and may need clinical-grade water. See medical/chronic-conditions.md § Dialysis water requirements and medical/infant-care.md § Formula and water safety. Allocate them their needs first; everyone else gets the remainder.
  5. Notify the household of the rules. Three rules, said out loud:
    • Drink only from the labeled potable container.
    • Flush only when there's a #2 — "if it's yellow, let it mellow" for 72 hours.
    • No baths, no showers, no laundry, no dishwasher until further notice.
  6. Cap or plug floor drains if a sewage backup is possible (rare but happens when the same main break disrupts sewer too — ask the utility). A flat rubber drain stopper or a pillow inside a contractor bag will do.

Decision criteria:

  • IF inventory < 1 gal × persons × days remaining → go directly to T+1 to T+6 hour sourcing. Do not wait.
  • IF anyone in the household is on dialysis → contact their dialysis center now. Centers have emergency protocols and may move the patient to a facility on a different water system. This is a clinical urgency, not a household-water problem.
  • IF the boil-water notice extends to neighbors not visibly affected → assume the entire pressure zone is compromised; sourcing water from a nearby unaffected neighbor's tap is not safe unless their address is confirmed outside the zone.

Failure modes:

  • "We have a Brita, we're fine": Carbon pitcher filters do not remove microbiological contamination. They are useless against the pathogens introduced by a mains break.
  • Counting partial inventory: A half-empty 5-gal jug is 2.5 gal, not 5 gal. Round inventories down.
  • Forgetting the water heater: A standard 50-gallon (190 L) tank water heater is the largest stored-water reserve in most homes. Don't bypass it without remembering it exists.

T+1 to T+6 hours — Sustain

Goal: Establish a routine that runs without thinking for the rest of the incident. Source more water if needed.

  1. Set up a hand-wash station at the kitchen sink. Two containers: one with a small amount of soapy water (a few drops of dish soap in 1 quart / 1 L of non-potable water), one with a clean-water rinse. After every bathroom trip and before every food-handling task, wet hands, lather 20 seconds, rinse from the second container. This is the single most consequential hygiene action of the entire 72 hours — most post-mains-break gastrointestinal illness traces to hand contamination, not the water supply itself.
  2. Source additional water if inventory is short. Options in priority order:
    • Buy bottled water from any store outside the boil-water zone. Standard 24-pack flats are 16.9 oz × 24 = ~3.2 gal (12 L) — inexpensive on a per-flat basis but the budget adds up fast for a household of four over 72 hours.
    • Borrow from a neighbor whose pressure zone is unaffected. Bring your own clean food-grade containers.
    • Tap a rainwater barrel if you have one, but only for non-potable use until you've boiled and (ideally) filtered it. See water/boiling.md § How long to boil.
    • As a last resort, draw from a surface water source — stream, lake, pond — and treat using the full purification stack (sediment filter → boil → chemical disinfection). This is for genuine scarcity, not convenience.
  3. Cook the perishables first. Anything in the fridge that needs water to cook (rice, pasta, dried beans) is expensive on your water budget. Pivot the menu to no-water foods: bread, peanut butter, canned vegetables and meats, fruit, crackers, cured meats, hard cheeses. See food/pantry-meals.md § No-cook meals. If you do cook, choose dishes that use the cooking water as part of the meal (one-pot pasta where the water gets absorbed, not drained).
  4. Switch dishware. Paper plates, paper cups, plastic utensils for the duration. The amount of water needed to properly clean dishes in a sink without running water is ~2 gallons (7.6 L) per meal for a family of four — that's a significant chunk of the budget. Disposables save 6 gallons (23 L) per day for a household of four.
  5. Plan toilet flushing. A standard low-flow toilet uses 1.6 gal (6 L) per flush; older fixtures use 3.5–5 gal (13–19 L). Manual flushing without using the tank: pour 1.5–2 gal (5.7–7.6 L) of non-potable water briskly into the bowl (not the tank). Use this technique only for solids; let liquid waste accumulate up to 3 flushes' worth in low-traffic bathrooms before flushing.

Decision criteria:

  • IF you have stored rainwater or graywater — use it for toilet flushing first, then for first-rinse on cookware, never for drinking without full purification (boil + chemical disinfection — see water/chemical.md).
  • IF the household includes someone with a compromised immune system (cancer treatment, HIV with low CD4, organ transplant, etc.) → do not use any unsealed water for handwashing, dishes, or cooking. Bottled-only until cleared.
  • IF you're sourcing water from a store, buy distilled (not just spring or purified) for any infant formula. Tap-zone bottled water is the second-best choice if distilled is sold out.

Failure modes:

  • Cross-contamination of the potable container: Anyone scoops with a hand or a cup that's been in non-potable water → the entire container is now non-potable. Use a dedicated dipper or spigot.
  • Filling a child's water bottle from the tap "just once": If the boil-water notice is in effect, that's an exposure. Coach kids that the rule applies to every fill.
  • Running the dishwasher because "it's almost finished from before": Anything that draws from the supply line draws contaminated water now. Don't.

T+6 to T+24 hours — Plan for the night

Goal: Move from acute response to a sustainable nightly rhythm. Refill anything that's running low.

  1. Pre-position water for the night. Bedside: a full water bottle for each person (16–24 oz / 500–700 mL). Bathroom: a 1-gallon (3.8 L) jug labeled "non-potable" with a cup, for nighttime hand-rinsing and any necessary toilet flushing. Kitchen: the labeled potable container, with the spigot or dipper visible.
  2. Brief the household on overnight rules. "Don't use the bathroom tap. The jug is the water. If you need a drink, your bedside bottle." Children should be walked through this once before bed. Most overnight contamination incidents are a sleepy adult or child using the bathroom sink from habit.
  3. Plan tomorrow's meals. Use the no-cook pantry meal list for breakfast and lunch. Dinner can be a one-pot meal using cooking water as part of the dish. If anyone is on a special diet (celiac, allergen-sensitive, diabetic), plan their meals first so the rest of the household isn't using their limited pantry options.
  4. Hygiene minimum standard: each person gets a "navy shower" using a damp washcloth and a small bowl of warm non-potable water — face, armpits, groin, feet. This is the bare minimum to prevent skin breakdown over a 72-hour window. See medical/hygiene.md § Austere hygiene routines. No shampoo, no full baths, no shaving unless essential.
  5. Check the utility update. Most water utilities post repair ETAs to a status page or social media within 4 hours of a major break. If the repair will extend past 24 hours, escalate your sourcing plan now — don't wait until your inventory is gone to start looking. Most retailers run out of bottled water 6–12 hours after a localized incident hits the news.
  6. Document for insurance. If there was any water damage (homeowner-side break, basement intrusion), take phone photos of every affected area now, before drying begins. Photos timestamped to the incident are insurance gold; reconstructions a week later are not.

Decision criteria:

  • IF the repair ETA is >24 hours → buy or borrow another 48 hours of water now. Don't ration into scarcity hoping the timeline holds.
  • IF anyone in the household shows signs of dehydration (dark urine, headache, dizziness on standing) — they've been under-allocated. Move them to 2 gal (7.6 L) per day allocation immediately. See medical/dehydration.md § Recognition.
  • IF a child under 12 months is in the house and formula water has been compromised → contact the pediatrician's after-hours line; some practices keep a 72-hour stash of pre-mixed formula for exactly this kind of incident.

Failure modes:

  • Sleeping through the night and waking up to find someone used the tap: The brief at bedtime is non-negotiable for this reason. Habit beats reason at 3 AM.
  • Bottled-water hoarding: Buying 200 gal of bottled water "just in case" leaves nothing for neighbors. Buy what you need for 48 hours past the current ETA, and leave the rest on the shelf.
  • Skipping the navy shower because "it's only 72 hours": Three days without bathing in active wear-the-same-clothes mode causes skin breakdown in the elderly, infants, and anyone with eczema. Don't skip.

T+24 to T+72 hours — Maintain or escalate

Goal: Run the established rhythm. Make the call about whether 72-hour DIY is still the right plan or whether you need to escalate to relocation.

  1. Daily inventory check. Every morning, count remaining potable water and divide by remaining days. If you fall below 1 gal × persons × days remaining at any check, source more that day — not "soon", that day.
  2. Re-test hygiene. Take a hard look at the kitchen and bathroom. Sticky surfaces, dirty handles, garbage piling up because dishes are taking longer than usual — these are the indicators that the routine is fraying. Reset by adding 15 minutes of cleanup to the morning routine.
  3. Re-brief the household daily. The three rules drift after 48 hours. A 60-second reminder at breakfast — "drink from the labeled container, don't flush yellow, no taps until the utility clears" — re-anchors the rhythm.
  4. Watch for the boil-water notice clearance. The utility tests water at multiple points in the affected zone, typically twice over 24–48 hours after repair. Clearance is published on the utility's status page, social media, and often a robocall to affected addresses. Do not drink, brush teeth, or wash dishes with tap water until the notice is explicitly cleared, regardless of whether pressure has returned.
  5. When pressure returns, flush the line before using:
    • Open the cold-water tap on the lowest level for 5 minutes.
    • Open every cold tap in the house briefly until water runs clear.
    • Replace any in-line filters (refrigerator water dispenser, whole-house sediment filter) — the post-break flush often pushes accumulated sediment into them.
    • Run the dishwasher and washing machine through one empty cycle on hot before resuming normal use.
    • Continue to use bottled water for drinking and food prep until the boil-water notice is cleared, even if pressure feels normal.
  6. Make the escalation call if needed. If the repair has stretched past 72 hours and your sourcing options are exhausted, escalate to one of these:
    • Temporary relocation to family, friends, or a hotel outside the affected zone. Use mobility/evacuation.md § Short-duration evacuation as the go-bag template.
    • Switch to the longer arc in guides/grid-down-survival.md § Water sub-system — a 5–7 day water-out scenario needs a different toolkit (large-volume bulk water purchases, possibly a gravity-fed water distribution ad-hoc setup from rain collection).
    • Call the utility for emergency water service. Most U.S. utilities will deliver pallet quantities of bottled water to vulnerable households (elderly, medical, infants) during extended repairs.

Decision criteria:

  • IF anyone in the household develops gastrointestinal symptoms (diarrhea, vomiting, abdominal cramping with fever) during the incident → start the oral rehydration solution protocol immediately and contact a clinician. Cholera and E. coli are real risks from compromised water, even if mostly from neighbors' compromised handwashing rather than the tap directly.
  • IF the basement intrusion was significant (more than a few cups of water) → start the mold-remediation 48-hour clock now; see threats/post-disaster-recovery.md § Mold prevention.
  • IF the household includes someone with a power-dependent medical device and the same incident is causing power issues → pivot to the no-power + medical-device household playbook; that scenario takes priority over the water playbook.

Failure modes:

  • Drinking tap water "for one quick sip" before the boil-water notice clears: this is how the post-incident illness cluster forms. The official clearance is the only signal.
  • Skipping the flush-the-line step: Drinking sediment-laden water right after pressure restoration can cause stomach upset even when the water is microbiologically safe.
  • Forgetting to replace filters: A 6-month filter just used 3 days of post-break sediment is functionally a 0-month filter from this point forward — replace it.

Cross-Foundation routing

If this becomes a problem Read this
Drinking-water supply runs out before utility restoration water/rationing.md § Resupply planning
Need to source from rain, stream, or pond water/sourcing.md § Source Type Decision Matrix
Need to boil and chemically disinfect found water water/boiling.md + water/chemical.md
Medication temperature breach develops medical/cold-chain.md § Cooler workflow
Infant formula water safety question medical/infant-care.md § Formula preparation
Dehydration symptoms in any household member medical/dehydration.md § Recognition and ORS
Basement intrusion + 48-hour mold window threats/post-disaster-recovery.md § Mold prevention
Need to coordinate with neighbors on shared sourcing community/mutual-aid.md § Rapid response
Repair stretches past 72 hours and evacuation becomes the call mobility/evacuation.md § Short-duration evacuation
Printable summary

Water main break — 72-hour playbook

T+0–15 min — Stabilize 1. Close house main shutoff valve (clockwise). 2. Open one low-level cold tap to relieve pressure. 3. Walk the street and yard; identify utility-side vs. homeowner-side break. 4. Call water utility's emergency line (not 911). 5. Brief household: one sentence, calm tone. Watch for: Seized shutoff valve — call utility for curb-stop closure if forced.

T+15 min–1 hr — Triage 1. Inventory stored water (bottled + drums + water heater + ice). 2. Calculate budget: 1 gal/person/day floor. 3. Separate potable (sealed bottled, water heater) from non-potable (older water, rainwater). 4. Identify elevated-need members (dialysis, infants, pregnant/nursing, ill). 5. State three rules: drink only labeled, flush only #2, no baths/showers/laundry/dishwasher. Watch for: Carbon pitcher filters do not remove microbes — useless here.

T+1–6 hr — Sustain 1. Set up two-container hand-wash station (soap + rinse). 2. Source more water if inventory short — buy / borrow / rain / surface. 3. Pivot menu to no-water foods (bread, PB, canned, cured). 4. Switch to paper plates and plastic utensils. 5. Plan toilet flushing: 1.5–2 gal pour, solids only. Watch for: Cross-contamination of the potable container is the #1 fail.

T+6–24 hr — Plan for the night 1. Pre-position bedside bottles + bathroom non-potable jug. 2. Brief overnight rules. 3. Plan tomorrow's no-cook breakfast and lunch. 4. Navy shower for everyone. 5. Check utility status page; document any damage for insurance. Watch for: ETA past 24 hr → buy 48 more hours of water now.

T+24–72 hr — Maintain or escalate 1. Daily inventory + budget check. 2. Re-brief household daily; rules drift. 3. Wait for explicit boil-water notice clearance — do not drink tap. 4. After pressure returns: 5 min cold-tap flush, replace filters, empty dishwasher + washer cycle on hot. 5. Escalate if needed: relocation, longer-arc plan, utility-assisted delivery. Watch for: First sip of tap water before clearance = illness cluster.

FAQ

How do I tell if a water main break is utility-side or homeowner-side?

The dividing line is the curb stop — usually marked by a small round metal cover at the property line. A break between the water main in the street and the curb stop is the utility's responsibility; a break between the curb stop and your house is yours. Symptoms of a utility-side break: water bubbling through pavement or pooling in the street, low pressure across the neighborhood, sinkholes forming. Symptoms of a homeowner-side break: soft wet spots in your yard along the service-line path, a slow drop in pressure isolated to your address, audible water-running sound from the basement near the service entry. If you're unsure, call the utility — they can do a remote pressure-test from their end in under 10 minutes.

Is water from the water heater safe to drink?

Yes — water heater contents are functionally a 40–80 gallon (150–300 L) stored-water reserve if the heater was running normally before the incident. Bypass the supply line first (close the cold-water inlet valve at the top of the tank), then drain from the bottom valve into a clean container. Discard the first quart (1 L) — that flushes any sediment that's settled at the bottom. The rest is potable drinking water, though it may be warm. See water/storage.md § Water heater bypass for the full procedure.

Can I drink the water in my toilet tank?

The water in the tank (not the bowl) is technically the same water that came from the supply line; if the tank water has been there for less than a few weeks and the tank doesn't have a chemical sanitizer cartridge, it's drinkable in emergency. The bowl water is contaminated. In practice, toilet-tank water is usually the last resort behind bottled, water heater, ice melt, and rainwater — not because it's not water, but because the psychological barrier is hard to overcome. If you're considering tank water, you should also be considering sourcing surface water and using a full purification stack.

What if the boil-water notice extends past 72 hours?

Extended boil-water notices are common after major mains repairs in older infrastructure — the utility has to test multiple points, and a single failed sample can reset the clearance clock. If the notice extends past 72 hours, three actions: (1) buy or arrange delivery of enough bottled water for the full estimated remaining duration plus 48 hours buffer — don't ration into scarcity, (2) shift to the longer-arc plan in guides/grid-down-survival.md § Water sub-system, (3) check on neighbors who may have less buffer than you — see community/mutual-aid.md § Rapid response.

Should I run my refrigerator's ice maker during the incident?

No — the ice maker draws from the supply line, which is either dry (utility-side break) or potentially contaminated (post-restoration before boil-water clearance). Leave the existing ice in the freezer in place; it's a usable potable reserve if the freezer was running normally before the break. After the boil-water notice clears, run a full ice-maker cycle (about 24 hours' worth of ice) and discard it before resuming normal use — the in-line filter and the ice maker's own reservoir may hold contaminated water.

Is it safe to brush my teeth with tap water during a boil-water notice?

No. Brushing teeth introduces water to the oral cavity and inevitably some is swallowed, even with disciplined rinsing. Use bottled water for tooth brushing for the duration of the notice. This is the single most-violated rule in post-mains-break incidents — most people remember to not drink the tap but forget about brushing.

What about pets — do they need the same precautions?

Yes, with one caveat. Dogs and cats are more tolerant of microbial water contamination than humans, but cryptosporidium and Giardia affect them too. Use the same potable supply for pets that you use for the household; do not save tap water "for the dog" during a boil-water notice. The exception is pets with compromised health (very young, very old, immunosuppressed, kidney disease) — use sealed bottled water exclusively, the same as you would for an immunocompromised human.

How does this scenario differ from a regional grid-down outage?

A water main break is localized — your immediate neighborhood is affected, the utility is responding, and the timeline is typically hours to days. A grid-down outage affecting water is regional — the entire utility may be without power for pumping, the timeline is days to weeks, sourcing options are far more constrained, and neighborhood coordination becomes essential. If you're unsure which scenario you're in, the diagnostic is: can you drive 15 minutes to a store and buy bottled water? If yes, this is a localized water main break and this playbook applies. If no, switch to guides/grid-down-survival.md.

When to escalate beyond this playbook

This 72-hour playbook is the right tool when the incident is localized, the utility is actively responding, and your household can source water externally if needed. Switch out of this playbook into a different response when any of these are true: the outage is regional rather than local (no nearby stores have water), the repair ETA stretches past 5 days, anyone in the household has a clinical complication that requires hospital-grade water management, or the same incident is affecting power, sewage, or natural gas simultaneously. For the regional case, see guides/grid-down-survival.md. For the multi-system failure, see guides/when-help-isnt-coming.md. For the clinical case, the utility can usually arrange emergency water service to medically-vulnerable addresses — call them and ask.

Tier 1 sources

Last reviewed: 2026-05-20 · Page Action Block: STANDARDS § 13 · Scenario format spec: SCENARIO-PLAYBOOK-FORMAT.md v1.1