Emergency water: storage, filters and treatment

Water is the first thing to get right. Store enough to ride out the first two weeks, then have a way to make more.

Updated October 2026. Prices are typical ranges; check the live price before you buy.

Some links on this page are affiliate links, marked Affiliate. If you buy through them we may earn a commission at no extra cost to you. It never decides what we recommend, and we include free options where they exist. How we pick and make money.

How much you need

Per person per day: 1 gallonHalf for drinking, half for cooking and basic hygiene. More in heat, for nursing mothers, and for the sick.
Short-term target: 3 daysThe traditional minimum. Fine for outages, too thin for earthquakes.
Recommended target: 14 daysWhat emergency managers in quake and hurricane regions now advise.
Pets: 1 oz per lbA 50 lb dog needs a bit over a quart a day.

When it matters

How important each item is in each kind of emergency.

All items, all emergencies

Water importance by scenario
Item	Outage	Grid down	Evacuate	Shelter	Bad water	Earthquake
Stored drinking water
Portable water filter
Purification tablets or bleach

Critical Important Useful

Stored drinking water: You can last weeks without food but about three days without water. Mains break in quakes and pumps stop in outages.
Portable water filter: Turns a creek, pool or rain barrel into drinking water once your stored supply runs out.
Purification tablets or bleach: Filters miss viruses. Tablets or unscented bleach cover that gap and weigh almost nothing.

Start here

Cheap, high-impact basics everyone should own.

Bathtub water bladder (WaterBOB or similar)

What it is: A food-safe liner that fills your tub with up to 100 gallons when a storm is forecast.
Why: The cheapest way to add a lot of water fast, as long as you get warning.
Watch out: Useless for surprise events like earthquakes. Pair with stored water.

$25 to $40Best for: Hurricane and winter storm regionsCheck price on AmazonAffiliate link

Sawyer Squeeze filter

What it is: A palm-sized hollow-fiber filter rated to about 0.1 micron, good for up to hundreds of thousands of gallons.
Why: Removes bacteria and protozoa from streams, pools and rain barrels. Light enough for every go-bag.
Watch out: Does not remove viruses or chemicals. Freezing can crack the fibers.

$30 to $45Best for: Every household and every go-bagCheck price on AmazonAffiliate link

LifeStraw Personal

What it is: A straw filter you drink through directly.
Why: Cheap enough to put one in each bag and the car.
Watch out: You can only drink at the source. A squeeze filter is more flexible.

$15 to $25Best for: Car kits and kids' bagsCheck price on AmazonAffiliate link

Step up

Where most prepared households land.

WaterBrick stackable containers (3.5 gal)

What it is: Rectangular, stackable, BPA-free jugs that fit under beds and in closets.
Why: The best density for apartments. Four bricks hold two weeks for one person.
Watch out: Heavy when full, about 29 lb each. Rotate water every 6 to 12 months.

$25 to $35 eachBest for: Apartments and small spacesCheck price on AmazonAffiliate link

Reliance Aqua-Tainer (7 gal)

What it is: A rigid jug with a spigot that has been a camping staple for decades.
Why: Low cost per gallon and easy to dispense from.
Watch out: At 58 lb full, it's not something to carry far.

$20 to $30Best for: Garages and car campingCheck price on AmazonAffiliate link

Katadyn Micropur MP1 or Aquatabs tablets

What it is: Chlorine dioxide or chlorine tablets for treating water.
Why: Kills viruses that filters miss. Weighs nothing.
Watch out: Needs 30 minutes to 4 hours depending on product and water temperature. Follow the label.

$10 to $20Best for: Bad-water scenarios and go-bagsCheck price on AmazonAffiliate link

Go deep

For long outages, big households and rural homes.

55-gallon water barrel kit

What it is: A food-grade drum with a bung wrench and siphon pump.
Why: Lowest cost per gallon and 55 days for one person in one footprint.
Watch out: Over 450 lb full. Put it on wood or a pallet, not bare concrete, and never upstairs.

$80 to $150Best for: Houses with a garageCheck price on AmazonAffiliate link

Gravity filter (Platypus GravityWorks, LifeStraw Family or similar)

What it is: A hanging bag filter that processes liters at a time with no pumping.
Why: The practical way to filter water for a whole family every day.
Watch out: Still pair with tablets or boiling if viruses are a concern.

$60 to $130Best for: Families planning for weeksCheck price on AmazonAffiliate link

How to choose

Store first, filter second. Stored water handles the first days. A filter covers the long tail.
Pick containers you can carry. Weight decides more than price.
Look for NSF/ANSI 53 or 58 or EPA-registered claims on filters and tablets, not marketing buzzwords.
Mark a rotation date on every container. Tap water stored in clean food-grade containers is generally rotated every six months.

Mistakes to avoid

Reusing milk jugs. They're hard to clean and degrade fast.
Storing jugs in direct sun or next to gasoline and chemicals. Plastic absorbs vapors.
Assuming a filter makes any water safe. Filters don't remove fuel, pesticides or most chemicals.
Forgetting the water heater. It's 40 to 50 gallons you already have.

Questions

How do I purify water with bleach?

Use plain unscented household bleach. The CDC guidance is 8 drops of 6% bleach or 6 drops of 8.25% bleach per gallon of clear water. Stir and wait 30 minutes. If it's cloudy, filter it first and double the dose.

How long does stored water last?

Water itself doesn't expire, but containers can leach and seals can fail. Rotate tap water every 6 months. Commercially sealed emergency water is often rated for 5 years.

Can I drink water from my water heater?

Yes, in an emergency. Turn off power or gas to the heater and close the cold-water inlet, then open the drain valve at the bottom. Let sediment run out first.

Is boiling or filtering better?

Boiling at a rolling boil for one minute kills pathogens, including viruses, but needs fuel. Filters need no fuel but miss viruses. Use both when you can.

How many days could you last?

Check off what you have. Get a score, your top gaps and a card to share. About 3 minutes, no sign-up.

Get your PrepScore