Disinfecting with household bleach

Bleach is a cheap and widely available product usually sold as a liquid 5% concentrate solution for a range of household uses from general cleaning and sanitisation to purifying water in an emergency.

When diluting with water for disinfecting objects and surfaces it should be mixed in small batches for daily use as it deteriorates over time.

Clean items or areas to be disinfected before applying the appropriate solution which should be prepared in a well ventilated area.

For clarity I will list the volumes in standard measurements as well as the ratio because in an emergency you might not have a measuring jug available but with a simple cup and bucket can achieve the correct mixture.


High level:

Ratio 1: 10 household bleach to water, called "strong" chlorine water by CDC

• 50ml bleach, 450ml of water

For sanitising known contaminated areas such as blood and other bodily fluid spills and critical medical instruments and areas leave to soak for ten minutes, and to prepare larger quantities of 1: 100 solution.

Sometimes it may be sold in different concentrations so this graphic helpfully shows the most common and the different ratios you need to get the same solution.  

Intermediate level:

Ratio 1: 100 household bleach to water, called "mild" chlorine water by CDC

• 5ml bleach, 495ml of water

Use to sanitise PPE, clothing and hard surfaces, after ten minutes wipe away any residue with clean water and a cloth if necessary.

At this level it can be used to sanitise hands if you are then able to rinse with clean water afterwards as it is still caustic, or to prepare quantities of 1: 500 solution for food hygiene. 

Low level:

Ratio 1: 500 household bleach to water

• 5ml bleach, 2495ml of water

To ensure surfaces and utensils are safe to prepare food as normal household cleaning and for washing fruit and vegetables that are to be eaten raw.

Bleach is toxic and can chemically burn so take care to wear appropriate PPE when handling it and never mix with ammonia or acids as this will produce harmful gases, many people have accidentally poisoned themselves pouring bleach into toilets after using acidic cleaners releasing chlorine gas into confined spaces such as a toilet is not a good idea!

Whilst it is not recommended in an emergency you can even add unscented bleach to water that you have collected to sterilise it for drinking rather than boiling it, at the ratio 1:25000 4ml bleach to 100l of water stir and leave it for at least 30 minutes before drinking.

Take care

Roo