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Safe Drinking Water During an Outage

Storing, rationing and using the water already in your home

5 minIntermediateUpdated 2026-10-23 Safe Drinking Water During an Outage

You will learn

Store enough water for your household for at least three days
Find the hidden water already inside your home
Respond correctly to a boil water notice

⚠️ Turn off the power or gas to a hot water tank before draining it, and let it cool to avoid scalds.

⚠️ Never drink from a toilet cistern that has had a cleaning tablet or block in it.

How much to store

Plan on 4 litres of water per person per day: 2 for drinking and 2 for basic hygiene and cooking. For a household of three, a three-day supply is 36 litres, which is about six 6-litre supermarket bottles or nine 4-litre ones. Add more for babies, pregnant women, people who are ill, pets and hot weather. Three days covers most local outages; a two-week supply is the target for areas with floods, storms or earthquakes. Store bottles somewhere cool and dark, away from petrol, cleaning chemicals and direct sunlight, and put the date on each one so you can rotate them.

💡 Sealed shop-bought water keeps for years if stored cool and dark. Rotate anyway once a year.

Filling your own containers

Food-grade plastic containers with tight lids work well; never reuse milk or juice jugs because protein and sugar residues feed bacteria. Wash the container with soap, rinse, then sanitise with 1 teaspoon of unscented bleach in 1 litre of water, swirl, wait 30 seconds, and rinse. Fill from a treated municipal supply. If your tap water is chlorinated by the utility, no extra treatment is needed. If it comes from a private well, add 2 drops of unscented bleach per litre before sealing. Label with the date and replace every six months. A clean bathtub liner can hold 200 litres for washing and flushing.

Water already in your home

When the taps stop, your house still holds water you can use. A hot water tank holds 100 to 300 litres: turn off its power or gas first, let it cool, then drain from the tap at the bottom. The toilet cistern, not the bowl, holds several litres of clean water as long as no cleaning tablet is inside. Ice in the freezer melts into drinking water. Canned vegetables and fruit are packed in liquid you can drink. If you know a pipe has failed or a flood is coming, turn off the main stopcock so contaminated water cannot enter, and fill sinks, pots and the bath immediately.

💡 Learn where your main stopcock is before you ever need it.

Boil water notices

Utilities issue a boil water notice when the supply may be contaminated, usually after a burst main, flooding or a treatment failure. Until it is lifted, boil all water for drinking, brushing teeth, washing food, making ice and preparing baby formula, using the 1-minute rolling boil. Dishwashers on a hot cycle above 65 degrees Celsius are fine; hand-washed dishes should be rinsed in water with a teaspoon of bleach per 4 litres. Showering is safe for adults if you avoid swallowing water. When the notice is lifted, run cold taps for five minutes and flush ice makers to clear old water from the pipes.

Stretching what you have

Drink what you need; rationing drinking water makes people ill faster. Save water elsewhere instead. Use hand sanitiser rather than washing, wipe dishes with paper before rinsing, and reserve grey water from washing for flushing toilets by pouring a bucket straight into the bowl. Cook foods that need little water, such as canned meals, and avoid salty snacks that increase thirst. Keep pets watered too; they cannot tell you they are struggling. If supplies run low, contact your municipality or civil protection service, which typically sets up water distribution points within a day or two of a major outage.

💡 Fill a bath before a forecast storm. That is 150 litres of flushing water.

Check yourself

How much water should you store per person per day?

Plan for 4 litres per person per day, half for drinking and half for hygiene and cooking, and more in heat.

Which container should you never reuse for water storage?

Milk and juice residues feed bacteria and are almost impossible to wash out fully.

Where in a home is there clean water during an outage?

The cistern holds clean supply water, provided no cleaning tablet has been added; the bowl is never safe.

During a boil water notice, which activity still needs boiled water?

Anything that goes in your mouth, including brushing teeth, ice and baby formula, needs boiled or bottled water.

Try it for real: Build a three-day water store

Count household members and pets and calculate 4 litres per person per day for three days
Buy or fill that amount, date each container and store it cool and dark
Locate your main stopcock and hot water tank drain and show another household member
Set a yearly phone reminder to rotate the store