Water when the taps stop

At a glance

• Water and wastewater utilities run on electricity. EPA lists pressure loss, boil-water advisories and reduced or stopped treatment as effects of a grid outage.
• Store at least 1 gallon per person per day. CDC says at least 3 days and a 2-week supply if possible. A 90-day plan for a family of four is 360 gallons.
• Your house already holds water: the water heater tank, ice, the toilet tank (not the bowl) and canned-food liquid (CDC).
• Boil clear water for 1 minute (3 minutes above 6,500 ft), or use 8 drops of 5 to 9% unscented bleach per gallon and wait 30 minutes (CDC).
• Filters do not remove viruses. Pair a filter with boiling or a chemical disinfectant.
• Water contaminated with fuel or toxic chemicals cannot be made safe at home (CDC).

Why the water stops when the power does

Most homes on city water never think about the pumps behind the tap. Treatment plants, booster stations and wastewater lift pumps all run on electric motors. EPA's power-outage checklist for utilities says losing grid power "may include pressure losses and boil water advisories, a reduction or cessation of water treatment, sewage back up and the discharge of untreated sewage." EPA's 2024 power resilience fact sheet adds that when pumps stop, a drinking water utility can stop producing finished water, and that backup power is not required under the Safe Drinking Water Act or the Clean Water Act.

The energy load is large. EPA says water and wastewater plants often account for 30 to 40% of a community's total energy use. EPA's own resilience planning treats short outages as 2 to 3 days and long ones as several weeks. Whether your utility has backup generators, and fuel for how long, is something to ask it directly. Over a long outage, pressure and treatment are not guaranteed.

Sewage is the other half of the problem. If lift stations stop, toilets can back up; our sanitation guide covers the two-bucket toilet that keeps stored drinking water from going down the drain.

How much water to store

CDC's rule is at least 1 gallon per person per day, for at least 3 days, and a 2-week supply if possible. Store more for pregnant women, sick people, pets and hot climates. Ready.gov now phrases it as 1 gallon per person per day "for several days," notes that a normally active person needs about three-quarters of a gallon a day for drinking, and says needs can double in heat. Oregon's Be 2 Weeks Ready program asks for enough water for 14 days. The gallon covers drinking plus basic sanitation, not showers or laundry.

Food adds to the total: freeze-dried meals are rehydrated with your stored water. ReadyWise lists about 120 cups (7.5 gallons) for its 120-serving bucket. Count that in when you read Long-term food storage.

Storing it: containers and rotation

1. 01Use food-grade containers. CDC says to use FDA-approved food-grade containers; otherwise choose ones with a tight lid, unbreakable material (not glass) and a narrow opening. Never reuse containers that held bleach, pesticides or other toxic chemicals.
2. 02Sanitize before filling. Wash the container, add 1 teaspoon of unscented 5 to 9% bleach per quart of water, shake, wait at least 30 seconds, empty and let it air-dry (CDC).
3. 03Fill from a safe tap and cap tightly. Label with the date.
4. 04Store at 50 to 70°F out of sunlight and away from gasoline and pesticides (CDC).
5. 05Rotate self-filled water every 6 months. For bought water, follow the expiration date (CDC). Keep it sealed until you need it.
6. 06Spread it out. Several 5- to 7-gallon jugs can be carried; a 55-gallon tank weighs about 460 lb full and stays where it is filled.

No. 1Water storage

WaterPrepared Blue 55 Gallon Water Storage Tank

Best for: Storing a month or more of household water in one footprint

• 55 gallons; 22 × 28 × 30 in
• HDPE, BPA free, FDA/NSF approved, UV-resistant blend (manufacturer)
• Built-in spigots that fit a standard garden hose, plus utility valves
• Large fill cap; stackable

Tradeoffs

• · About 460 lb when full (55 gal × ~8.3 lb, our arithmetic), so fill it where it will stay
• · No pump or water treatment included in this listing

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

No. 2Water storage

Reliance Jumbo-Tainer 2.0, 7 Gallon (08630-03)

Best for: Rigid, refillable storage you can rotate

• 7 gal / 26 L
• 15.3 × 8.5 × 18.0 in; 2.9 lb empty
• Food safe: LFGB certified and FDA compliant
• PFAS- and BPA-free
• Leak-proof hideaway spigot; dual handles

Tradeoffs

• · Reliance does not list it as stackable
• · About 58 lb when full (7 gal × ~8.3 lb plus container)

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

No. 3Water storage

waterBOB Bathtub Emergency Water Storage

Best for: Filling a large volume fast when a storm is forecast

• Holds up to 100 gallons
• 10 mil food-grade LLDPE liner
• Fills in about 20–30 minutes
• Siphon pump included
• Designed for one-time use

Tradeoffs

• · Single use
• · Manufacturer notes most standard bathtubs hold about 60–70 gallons, so real capacity is often lower

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

A bathtub liner is for the day before a forecast storm, not for long storage. The emergency water storage chapter of the Blackout Kit compares more containers.

Water already in your home

When stored water runs low, CDC lists safe sources inside the house:

• The water heater tank that feeds your faucets. Do not use a heating-system radiator tank.
• Ice made from uncontaminated water, melted.
• The toilet tank, not the bowl, if the water is clear and has no cleaner added.
• Liquid from canned fruit and vegetables.

FEMA warns against water from radiators, hot-water boilers and waterbeds, because fungicides or chemicals in the vinyl may make it unsafe. FEMA also says not to drink water from swimming pools, spas or collected rainwater. CDC allows pool and spa water for hygiene and cleaning, "but not for drinking." Ready.gov's blunt rule: "Never ration drinking water unless ordered to do so by authorities." Drink what you need today and find more tomorrow.

Making water safe to drink

Boiling: the most reliable method

CDC: bring clear water to a rolling boil for 1 minute, or 3 minutes above 6,500 feet. If the water is cloudy, let it settle or filter it through a clean cloth first. Boiling needs fuel, so plan for it alongside cooking fuel in Heating without power. Never run a camp stove or grill indoors.

Bleach

Use only plain, unscented household bleach, and check the label for the sodium hypochlorite percentage. Ready.gov gives the equivalent dose as 1/8 teaspoon per gallon for 5.25 to 6% bleach.

Other chemical treatments

CDC says chemical disinfectants kill viruses and bacteria but may not kill parasites. Chlorine dioxide kills Cryptosporidium; iodine and chlorine tablets do not. People who are pregnant, have thyroid problems or are sensitive to iodine should avoid iodine-treated water, and nobody should drink it for more than a few weeks.

Filters

CDC says portable filters "will not remove viruses." To remove Giardia and Cryptosporidium a filter needs an absolute pore size of 1 micron or smaller (look for NSF 53 or 58 cyst reduction); for bacteria, 0.3 micron or smaller. Filter first, then disinfect. A gravity filter is the practical household choice for a long outage because it processes gallons without pumping.

No. 1Water treatment

Platypus GravityWorks Water Filter System, 4.0 L

Best for: Filtering household volumes without pumping or squeezing

• 0.2-micron hollow-fiber filter; filters up to 1.75 liters per minute (manufacturer)
• Removes 99.9999% of bacteria and 99.9% of protozoa (manufacturer)
• Filter life up to 1,500 L
• 4.0 L dirty reservoir plus 4.0 L clean reservoir; 11.5 oz

Tradeoffs

• · Manufacturer spec table lists it as not effective against viruses: boil or disinfect when viruses are a concern
• · Hollow fibers can be damaged if the filter freezes while wet

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

No. 2Water treatment

Sawyer Squeeze Water Filter System (SP129)

Best for: Reusable all-rounder: squeeze, gravity or on a bottle

• 0.1-micron absolute hollow-fiber filter
• Removes 99.99999% of bacteria and 99.9999% of protozoa such as Giardia and Cryptosporidium (manufacturer)
• Filter about 3 oz
• Reusable BPA-free collapsible pouch
• Lifetime limited warranty

Tradeoffs

• · No virus claim: disinfect after filtering if viruses are a concern
• · Manufacturer page lists no filter life in gallons

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

No. 3Water treatment

Katadyn Micropur MP1 Water Purifier Tablets (20 tablets)

Best for: A purifier backup that covers viruses as well as bacteria and cysts

• Chlorine dioxide tablets: one tablet treats 1 liter of clear water
• 20 tablets treat up to 20 liters (a 30-tablet pack is also sold)
• Effective against bacteria, viruses and cysts such as Giardia and Cryptosporidium (EPA-registered label)
• 4-hour treatment time; react in an opaque container or in the dark
• Shelf life 5 years from date of manufacture (manufacturer)
• EPA Reg. No. 70060-22-39444

Tradeoffs

• · Four hours per liter is slow for a household; use it for drinking water, not bulk
• · Small volume per pack: 20 liters is about 5 gallons

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

Sun and distillation

CDC describes solar disinfection for clear water only: fill clear plastic bottles and leave them in direct sun for 6 hours, or 2 days if cloudy. Ready.gov describes distillation: boil water for 20 minutes and collect the vapor that condenses. Distillation removes salts, heavy metals and most chemicals, but it is slow and fuel-hungry.

Rainwater: useful, not automatically safe

CDC says rainwater "is not necessarily safe to drink without first removing germs and chemicals." Roofs, gutters and pipes can add lead, copper or asbestos, and bird droppings are a risk, especially after dry spells. Collecting rainwater is not allowed everywhere, so check local rules before installing barrels. In a long outage, rainwater is best used for flushing, washing and garden use, and treated before drinking: filter it, then boil or disinfect.

If you are on a well

A well pump is an electric pump: no power, no water, from the first minute of the outage. CDC warns that "loss of power or water pressure can lead to contaminated well water." If water spurts from a faucet when power returns, the well and plumbing lost pressure; CDC says not to drink the water until it is tested, and to prime the pump, then disinfect and flush the well. CDC says to use a generator to run the well if appropriate, never indoors; the connection should go through a transfer switch or interlock installed by a licensed electrician.

Well pumps draw a lot of power at startup, so size any backup with real numbers. The backup power calculator on our sister site BackupPowerAI adds up your loads.

A grid-down water checklist

• Store 14 days at 1 gallon per person per day now; work toward 30 days.
• Date and rotate self-filled water every 6 months.
• Know how to drain your water heater and where the shutoff is.
• Keep unscented bleach, a dropper and a gravity filter together.
• Keep fuel and a stove for boiling, used outdoors only.
• Plan a toilet that does not use drinking water.
• Record totals in the Blackout Kit worksheet and tick them off on the blackout checklist.

What we don't know

There is no public, nationwide figure for how long each city's water system holds pressure without grid power. It depends on elevated storage, gravity-fed zones and whether the utility has backup generators and fuel, which federal law does not require. Ask your water utility directly. Filter makers' removal figures are their own claims. The safest assumption for a long outage, such as a severe solar storm, is that treated tap water may stop or become unsafe within days, which is why the 30-day plan and 90-day plan start with water.