Liquid soap vs solid soap bars, what’s more sustainable?

Updated: Jun 26, 2021

We talked about solid and liquid soaps in our Swap of The Week section of our email. Not a subscriber yet? Sign up to our mailing list to get these tips straight to your inbox every week!

Liquid soaps have become so popular that they predominantly line the store shelves at the supermarket… but solid soaps are making a comeback with the support of a community looking for less wasteful packaging solutions. For a long time solid soaps got a bad rap, so we break down the facts.

2 myths about Solid soap vs Liquid soap

Is a liquid soap more hygienic or safe?

Both soaps will reduce the number of pathogens on your hands, because the soap molecules are designed to break up the oils that naturally build up on our skin, loosening it up along with all the present dirt and microorganisms and micro when you rub your hands. These soap molecules are also water-loving, or “ hydrophilic” though, so when you rinse your hands, off they go with your tap water!

According to Stanley Maloy, PhD, Associate Vice President for Research & Innovation at San Diego State University, foaming liquids may be less effective than liquid because they are dispensed already sudsy, whereas liquid needs to be worked up. So if you are fond of your liquid dispenser, skip the supermarket foam and refill at the bulk store on simple liquid!

Not all bar soaps are created equal; look out for those with fewer ingredients and that use natural oils and essences. Beyond the soaps used for your body, those used for laundry or use around the house keep you exposed to those chemicals so what they contain really matters. These chemicals also wash out down the drain or in other countries (where you might travel to!) directly into nature if there are no or poor waste water treatment systems, polluting the surrounding environment and aquatic life.

Liquid soap vs bar soaps: which is cheaper?

We often hear “ a low-waste lifestyle is so expensive”. Really? According to a comparative study, a regular 30 second hand wash consumes on average just 0.35 grams of bar soap - compared to one pump of 2.3 grams of liquid soap! That’s 6 times less product for using soap! Liquids are also full of “aqua”, just a fancy word for ...water! Why pay more for a less effective product? Liquids also typically cost more, and even at the bulk stores! Switching to a solid soap means buying less product for more effectiveness at a cheaper price, so it’s a win-win all around!

You can recycle your soap slivvers for a truly zero waste bathroom and home! And now onto our real question

Liquid soap vs soap bar: which is more sustainable?

This is the real question we love at barePack! The resources needed for making equal amounts of solid soap and liquid soap are not at all equal: solid soaps use less.

Carbon footprint

While soap is clearly not the most determining factor of your carbon footprint (unlike your transportation or diet), it’s important to know what factors make soap bars less carbon intensive than liquid soaps, because you can use this knowledge to make better decisions concerning other products.

In a research by Zurich’s Institute of Environmental Engineering that looked at the overall environmental impact, taking into consideration the production and use of liquid and solid soaps, liquid soap turned out to produce ten times more carbon emissions than bar soap due to the added synthetic chemicals that require energy to make. Liquid soaps also rely on specific plastic dispensers, many of which are tough plastics and made of several plastic types and in all are more energy-intensive to manufacture than a simple pulp-based box.

During transportation, solid soaps are light years ahead in the game: more efficient (stackable) and lighter compared to soap dispensers. If you are refilling a battle at a store you might think you get away with it, but even the store requires large dispensers that are delivered to them in order to serve you. Solid soaps simply can’t be beaten here, resulting in fewer deliveries for sellers (also less costs and simpler inventory management) and lighter loads, so less carbon emissions.

Water consumption and land usage

Chemicals found in the liquid soaps require more wastewater treatment however there’s a slim advantage to liquid soaps when it comes to land usage because most bar soaps contain vegetable oil derivatives that are farmed crops. This is particularly true when comparing to a bar soap that uses palm oil, the monocrop that is destroying biodiversity in our neighbouring countries. But don’t be fooled, palm oil-derived products (there are over 200 different names for palm oil!) also make their way into liquid soaps, they just use less because water is the main ingredient.

Packaging and end-of-life

Where liquid soaps fail the most. As mentioned, it costs more resources to make but on top, complex dispensers whose different plastics are assembled together and cannot be separated will likely not get recycled. On top, they often come with shrink wrap to avoid tampering in stores, and that cannot be reused for sure! That said, if you buy soap bars in the supermarket, they usually come in a cardboard box in a shrink wrap that you can’t see (an unpleasant surprise when you thought you had managed to make it a disposable plastic-free buy!).

How to switch to soap bars

Now you know you want to move to soap bars, it might take a while to phase them out, which gives you the chance to research on which options are available, where to get them, and slowly replace them as you run out. Remember that as with all detergents and body products, you might need to test a few formulas before you find the right one for you.

Where to buy eco-friendly soaps?

Switching to bar soap bars can cut down a great amount of plastic consumption. To avoid the single-use packaging, head over to a bulk store and bring your own silicone box, bag, or metal tin box to store them in (especially as we live in a warmer-than-most-countries climate!). Bulk stores can be local stores as well as some leading beauty brands such as Lush, who have been making soap bars since day one.

Support Local and packaging-free

Local bulk stores you can visit here in Singapore: Eco.Le, The Source, Scoop Wholefoods, The Green Collective... Such shops also offer refills for your liquid soaps so that if you do really like them, you can avoid buying new bottles every time.

Singapore is small but we’re lucky to have our own independent handmade soap crafters such as Artisan’s Garden.

Do you have a favourite soap? Where do you get it from? Share with the community and help someone make a swap today!

Let's stay in touch

Like our blog and information? Then sign up for our updates and to learn more on sustainable living - the practical way.