Hot Water Vs Cold Water

Nappies are heavily soiled laundry, hot water is the most effective way to remove soiling. All laundry detergents can be used in cold (30⁰C), warm (40⁰C) or hot (60⁰C) water, however, a hot wash will outperform every time.

Why is hot water more effective at removing soiling and stains?

Heat breaks the chemical bonds of the soiling and stains, which means textiles are going to be cleaned better in hot water. This applies to all fabrics which are not heat sensitive eg cotton, bamboo/viscose, hemp, rayon, polyester.

The elevated temperature helps the raw materials in the detergent work. Sodium percarbonate (oxygen bleach) needs warm-hot water to work, and enzymes don’t work in cold water.

But enzymes denature and stop working above a certain temperature?

Correct, but heat is far more effective at breaking the chemical bonds of soiling, than enzymes are!

Why were enzymes added to detergents?

So that laundry could wash at 40⁰C.

What temperature should I use to wash my cloth nappies?

Whatever temperature suits your circumstances and situation. Ideally cloth nappies should be washed at 60⁰C because you are less likely to have smell or staining problems, and less likely to have ammonia develop. But not everyone can for one reason or another. We recommend washing cloth nappies in 40-60⁰C, see our Wash Routine Basics for more information.

What temperature should I wash the rest of my laundry?

Whatever temperature suits your circumstances and situation. Ideally linen, towels, clothing or items covered in food, dirt etc, will come out of the machine much cleaner at 40-60⁰C. Darks and coloured clothing may start fading over time at 60⁰C, so 40⁰C is a better option for these items.

While cold washing saves money on energy costs, the down side is eventually smells will occur. Lower washing temperatures result in higher microbial levels in the washing machine and laundry, more microbes means more smells.

As a result of this basic chemistry, and after extensive testing by our Clean Cloth Nappies Admin team and feedback from members, we can state with certainty that washing cloth nappies in cold water does not work in the long term. Nappies just won’t come out clean, smell and stain free out of the wash, if washed in cold water in the longer term. What do we mean when we say clean? They should come out of the washing machine after main wash as clean as they were when they were new.

What if I don’t have hot water available?

Don’t worry! Modern Front Loader machines heat their own water. Traditional Top Loaders or High Efficiency Top Loaders require a hot water tap connection. If a hot water source is not available for a Top Loader, an option is to do a cold pre wash cycle, then bucketing in warm/hot water into the machine for the main wash. Alternatively, sanitise with chlorine bleach once a week-fortnight. Sanitising with chlorine bleach will oxidise ammonia and kill any remaining bacteria which can cause rashes.


References

  1. Textile Quality Depletion due to Household Machine Wash – Ways to Measure and Impacts of Wash Duration and Temperature on Textiles.
  2. Marlitt Honisch, Britta Brands, Mirko Weide, Horst-Dieter Speckmann, Rainer Stamminger and Dirk P. Bockmühl, Antimicrobial Efficacy of Laundry Detergents with Regard to Time and Temperature in Domestic Washing Machines.
  3. Dr Chemical, The Chemistry of Clothes Washing #8: Hot or Cold <https://www.drchemical.com.au/chemistry-at-home/laundry/the-chemistry-of-clothes-washing-8-hot-or-cold>.