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Soap and Sustainability

Soap and Sustainability

How sustainable is your lather? The big question seems to be whether bar soap is more sustainable than liquid soap.

After writing my recent article ‘Homemade Beauty and Sustainability’ for Sourced by HuffPost UK my curiosity got the better of me and I looked further into the sustainability of soap as this is where my green beauty journey started.

An interesting study was carried out by two researchers at the Swiss Institute of Technology to look at the sustainability of bar soap vs liquid soap.

The researchers came up with some interesting results:

  • Bar soap requires one fifth of the energy to produce compared to liquid soap.

  • Liquid soap contains significantly more water than bar soap which means more water is used in the production process and this also makes liquid soap heavier to transport.

  • Liquid soap can use up to 20 times more packaging than bar soap. The plastic bottles are also bulkier for recycling purposes and thus use more energy to recycle.

  • When handwashing with liquid soap we use a lot more of the soap compared to bar soap. However, on the flip side when we use bar soap it seems that we use about 42% more water.

Is bar soap or liquid soap better for our environment?  To conclude, in the words of Koehler and Wildbolz:

“Hand-washing with bar soap overall proves to be preferential to liquid soap for all indicators studied.”

This study certainly provides food for thought or should I say soap for thought!


Koehler, A. and C. Wildbolz. Environmental Science & Technology. Published 2009 doi:10.1021/es901236f (online at :