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The Environmentalist's Perspective: Liquid vs Bar Soap

Updated: Dec 26, 2020

The humble bar of soap has made a grand return to popularity in the latest decade. The 1980s saw a switch in the western world from bar soap, which had been the commonplace option for centuries, to liquid soap mass produced in plastic bottles. Now, with a return to interest in sustainability and simplicity, the West is returning to the trusted bar of soap. From reduced emissions to healthier ingredients, there are many reasons that bars of soap are the greener choice when pitted against liquid soap.





Lifespan

Studies have shown that we use significantly less bar soap to wash our hands than we do liquid soap. Because you need to rub a soap bar in your hands to create a lather, we tend to take just the amount of soap that we need. This is not the case with liquid soap. Soap dispenser manufacturers often make dispensers that portion out more soap than what is really needed. Presumably, this is to ensure that you will be back to buy more sooner rather than later. Researchers at the Zurich Institute of Environmental Engineering found that per average handwashing, people use 0.35g of bar soap vs 2.3g of liquid soap (Koehler and Wildbolz, 2009). This translates to using 6x more liquid soap than bar soap per wash.


Transportation

Liquid soap is mainly composed of water. Take a look at a bottle of liquid soap, and you are virtually guaranteed to find that the first ingredient is water. Not only does this make for a far less potent product, but it also increases shipping emissions to account for the added weight of the water. Additionally, liquid soap is usually packaged in cylindrical shaped bottles, making them difficult to stack efficiently for compact transportation. Bars of soap can be packed tightly together during transport, saving space on the transport vehicle and ultimately more product to be transported per delivery, reducing fossil fuel emissions.


Packaging materials

Bar soap has the obvious environmental advantage in the packaging department, often having no more than a small paper label and a cardboard box for safe travel. This is in stark contrast to liquid soap, which is packaged in bulky plastic bottles that are generally not even recyclable. Furthermore, these plastic bottles require 20x more energy to produce than their bar soap counterparts. Even more eco friendly soap dispenser options, such as those made from glass or metal, require far more energy and raw material to produce in comparison to the paper packaging of bar soap.


Energy

Liquid soap requires at least 5x more energy to produce than bar soap does.


Ingredients

Liquid soap isn't technically soap. Instead, it is actually detergent. Liquid soap often contains petroleum-based ingredients, chemical stabilizers, preservatives, parabens, artificial fragrances and colors, and emulsifiers. Many liquid soaps have a toxic effect on the environment and require intensive processing at water treatment facilities to be neutralized, thereby requiring even more water and energy. While bar soaps surge in popularity, we are also seeing an increased interest in natural, biodegradable, handcrafted bar soaps that are significantly healthier for both you and the planet.



From the environmentalist's perspective, bar soap is the clear winner of this soapy battle. With so many naturally scented and colored soaps to choose from today, the switch from liquid soaps and body washes to solid soap has never been more enjoyable!



Citations

Koehler, A., & Wildbolz, C. (2009). Comparing the Environmental Footprints of Home-Care and Personal-Hygiene Products: The Relevance of Different Life-Cycle Phases. Environmental Science and Technology, 43(22), 8643-8651.