How to make water safe to drink under a boil water notice

When a boil water notice is in place, boiling is the most effective way to disinfect tap water. But there are some other ways you can do this. 


Boiling water is the most effective way to disinfect water, as it will kill all disease-causing bugs.

Use boiled water for drinking, preparing food, cooking, making up infant formula, handwashing, and cleaning your teeth.

Find out what you need to use treated (boiled) water for when a boil water notice is in place

How long to boil the water

Boil the water in an electric jug until the jug turns off automatically.

Or bring the water to a rolling boil (where bubbles appear in the centre and do not disappear when the water is stirred) for one minute.

Store cooled boiled water in a clean container with a lid. 

Boiled water is best used within 24 hours and can be boiled again to be sure it is safe. This is especially important for preparing infant formula.

What to do if you don’t like the taste of boiled water

Boiled water can taste a bit flat. To improve the taste, you can:

  • pour cooled water back and forth from one clean glass into another to add air to the water
  • let the water stand for a few hours
  • add a pinch of salt to each litre of boiled water
  • chill the water in the fridge.

Commercially bottled water

If your tap water is unsafe to drink, you may choose to use bottled water if it’s available.

Keep bottled water in its original container and do not open it until you need to use it.

Bottled water may be used for drinking, cooking, and hand washing with no further treatment.

What to do if commercially bottled water is past the expiry date

Many manufacturers advise a two-year period for taste, but bottled water can be used indefinitely if stored properly.

Store commercially bottled water at room temperature (or cooler), out of direct sunlight and away from solvents and chemicals such as petrol, paint thinners and dry-cleaning chemicals.

If the water appears cloudy, then it should be treated (e.g. by boiling or adding bleach) before drinking.

Purification tablets

If you are unable to boil your water or add bleach, purification tablets can be used to disinfect the water.

Follow manufacturer’s instructions for details on how much to use. 

Using bleach

Boiling water is the most effective way to disinfect water, as it will kill all disease-causing bugs.  If it’s not possible to boil water, e.g. in a power outage, disinfecting the water by adding bleach is effective for killing most bugs. 

Bleach is a compound (mix) of chlorine known as sodium hypochlorite. Chlorine compounds are often added to drinking water to get rid of disease-causing bugs.  The use of chlorine has been a major factor in reducing illness from waterborne diseases around the world.

How to disinfect water using bleach

First, make sure you have the right kind of bleach. Only use plain, unscented bleach.

Some products contain additives could make you sick. Do not use bleach that contains:

  • cleaning chemicals (surfactants), which make the water foam or bubble when it is shaken or mixed
  • added scent or perfume
  • any other additives. 

If the product's label is not clear about what has been added to the bleach, do not use the product for making water safe to drink.

Once you are sure that you have plain, unscented bleach: To disinfect the water add 5 drops of bleach to 1 litre of water or 1/2 teaspoon to 10 litres of water. Stir and leave the water to stand for 30 minutes before drinking.

What to do if your water turns blue (or black) when you add bleach

Some water sourced from the ground and contains minerals. Some of these minerals can react with the bleach and change the colour to blue or black. While not hazardous, it is not aesthetically pleasing. 

What do to if your bleach has expired

If there are no alternatives available, use your bleach and double the dose.  You can double the dose with no adverse health effects. 

What to do if you don't like the chlorine taste of bleach 

To improve the taste, store your treated water in the fridge. Not only will the chilled water taste better, but it will also lose that chlorine smell.

Keep the jug covered and preferably do not keep any water for more than 24 hours.