Sustainable Soap: A Deeper Dive

by Fred Horch, Principal Advisor

How to choose and use sustainable cleaning products.

When I asked my friends, “What are your sustainability goals?” I wasn’t expecting, “Making my own soap.” But that’s actually pretty interesting. In my last post I shared home-made soap and laundry detergent recipes. This post is about choosing and using sustainable soap and cleaning products, leaving the making of them to someone else.

I’ll show a few cleaning products my family uses and explain why by exploring the “Goods,” “Water,” and “Energy” pathways to sustainability. And I’ll share a seven-dimensional sustainability scoring system you can use to evaluate any product for your own home — and ultimately to help make the world better for everyone.

The scoring system will seem insanely complicated — and it is if you try to score every product by hand. But thanks to the miracle of modern computers and the Internet, I’m developing a web app that does the calculations. All you have to do is answer questions about products you care enough about to dig into, and you’ll get a meaningful score that tells you which ones really are more sustainable than the others.

But before that, here’s a shout out to my friend Joe Walsh, owner of Green Clean Maine, one of the awesome Maine businesses On the Pathway to Clean Energy, a volunteer project I’m managing. He really knows how to make sustainable cleaning supplies. The very easiest way to use sustainable cleaning products in your home is to hire a service like Joe’s.

What Is Sustainable Soap?

When I was a kid, I thought soap killed germs by dissolving their cell membranes. That’s not how it works. Soap and detergent and water remove the habitat (dirt and grime) that harbor germs, but they are not germicidal disinfectants. To kill germs, use something like bleach, peroxide or alcohol.

What about over-the-counter “antimicrobial” soaps containing triclosan or triclocarban? According to the Food and Drug Administration, “manufacturers haven’t proven that those ingredients are safe for daily use over a long period of time.”

To use soap or detergent to get things clean, the main task is getting the particles of dirt and oils stuck onto one end of a soap molecule. Rubbing your hands, scrubbing your dishes, or agitating your clothes are good ways to get soap in contact with the grease and grime you want to remove. Then clean water can rinse it away.

Little droplets of oil stick to other oil droplets, while water droplets stick together. But a soap molecule sticks to both: its tail sticks to oil and its head sticks to water. If you can smoosh up some oil against one end of a soap molecule, you can get oil to mix in with water.

A soap molecule has a tail that likes oil, and a head that likes water.

In the 1960s, enzymes started being added to detergents to make them work better. Enzymes in cleaning products are proteins, usually produced by microbes, that accelerate chemical reactions to break apart big molecules into smaller molecules to remove stains and odors. According to the Household & Commercial Products Association:

Enzymes work at mild conditions, which means they can function at low temperatures and mild pH. In addition, enzymes are only required at low concentrations in cleaning products to be effective. Enzymes are also readily biodegradable, resulting in no negative environmental impact.

— The Role of Enzymes in Detergent Products

Sustainable soap sticks to grease and water, and maybe contains enzyme proteins to accelerate chemical reactions, but doesn’t cause environmental or health problems.

Sustainable Soap and Cleaning Products

Here are a few cleaning products with positive sustainability scores that my family uses. If you’re more interested in how to calculate sustainability scores yourself, skip to the next section.

A few of the sustainable cleaning products we use in our home.

For hand soap, I’ve settled on fragrance-free liquid from simplehuman. This works well in hand pumps, whereas some other brands have tended to dry out my skin or gum up soap dispensers. That clear refillable glass soap pump came from GoGo Refill.

For hand dishwashing soap, the ecover zero is just a sturdy bottle I’m reusing. I buy Ecos dish soap in bulk. Ecos also makes a nice parsley-scented all-purpose cleaner available in gallon refills.

Buying in bulk saves me time and money and improves the product-to-packaging ratio factor in the sustainability score for products suitable for bulk buying.

For sponges, I buy packs of slim cellulose sponges, which break down more easily in my compost pile than thicker sponges. For our automatic dishwasher (and for our ventless clothes washing and drying machine) we buy Dropps.

Baking soda, alcohol, and vinegar: better living through chemistry!

For scrubbing, we use Bon Ami (hasn’t scratched yet!). Rounding out our arsenal of cleaning products are the old standbys of baking soda, alcohol and vinegar. The cleaning products we use in our home all score well along seven pathways to sustainability.

Scoring Products

Back when I was running F. W. Horch Sustainable Goods & Supplies, as a busy business owner with a sustainability reputation to uphold, I needed a quantitative, thorough, and trustworthy way to decide which products deserved shelf space. The seven-dimensional sustainability scoring system that I developed, I am expanding and sharing in my Handbook for Sustainability so you can use it to choose sustainable practices, products and services for your home or organization.

Be forewarned: this scoring system is comprehensive! I spent many years selecting products for my store and talking with customers about what factors were important to them. These conversations are the basis for my very extensive checklist for scoring sustainability.

Why Do I Need the Product?

In my sustainability scoring system, the first step is to identify a need, such as:

• Washing hands.
• Washing hair.
• Washing dishes.
• Washing clothes.

One kind of soap could satisfy all of these needs. (Dr. Bronner’s for everything!) But the difference in pH between hands and hair and the effectiveness of cold-water enzymes to remove clothing stains are reasons to choose different products.

After deciding why I need a product, then I study how products work. Reading hand-washing articles from the Centers for Disease Control and the Food and Drug Administration convinced me that I did not need antimicrobial hand soap. Then, personal experience with preservative-free soaps convinced me that antimicrobial agents in moderation can keep soap from growing mildew and smelling bad.

Exploring Pathways

Sustainably satisfying a need is deciding among practices, products and services that meet the need in a way that makes the world better for everyone. I’ve come up with a way to consider seven pathways to sustainability while asking the question, Will this choice make the world better or worse?

Let’s explore the seven pathways to see which apply to washing hands:

1. Energy: Probably, if we wash in warm water.
2. Food: I usually wait to eat until after I wash my hands.
3. Water: Yes, frequently we’ll be using water to wash our hands.
4. Movement: Not much travel required to wash hands in my house.
5. Goods: Definitely, if we use soap.
6. Habitat: Can’t see a strong connection.
7. Community: Always good to share best practices — like with this article!

Three of the pathways — “Goods”, “Water,” and “Energy” — seem especially important for hand washing. Along those pathways I’ll take measurements or make assessments to assign subjective but quantifiable points adding up to a pathway score. Then I’ll combine pathway scores into a single sustainability score so that I can decide what to do.

Mathematically, a quantitative score based on seven pathways to sustainability is a vector in seven-dimensional sustainability space. Computers are very good at calculating vectors; I’m developing a web app that makes it easy to calculate sustainability scores.

A positive sustainability score means making the world better for everyone, while a negative score means making the world worse.

Along the “Goods” Pathway

The “Goods” pathway assigns points for the lifecycle environmental and health impacts of a product, from manufacturing, to distribution, to disposal.

Satisfaction Points: How Well Does It Work?

How well does this product satisfy my need? I usually rate from zero satisfaction points for terrible to ten for terrific. Product that don’t work get negative points.

Affordability Points: How Affordable Is It?

Many of the environmental and social costs of a product (but not all of them) are reflected in the price. If public policies are designed well (i.e. if polluters pay for pollution, etc.), the worse the negative impacts, the higher the price.

Affordability points are the inverse of price per unit, so more affordability means fewer negative impacts. For example, a popular recipe for making your own soap requires “goat’s milk glycerin melt & pour soap base” ($0.81/ounce). Normalizing that price to find how many ounces you can buy for a dollar gives 1.234567 affordability points. The soap I like to buy (simplehuman fragrance free for $0.24 per ounce) gets 4.166667 affordability points when I plug in the cost per ounce into my sustainability app.

Ingredient Points: How Problematic Are the Ingredients?

Ingredient points measure how problematic (or beneficial) the materials in the product are. You can make soap from animal fats or vegetable oils and lye from wood ashes and rainwater. Plentiful and renewable, these are not problematic ingredients.

What makes an ingredient problematic?

• Being scarce. Soap made from whale oil would not be sustainable.
• Being unnecessary. Fragrances, colors, and foaming agents aren’t necessary in soap. The resources, time and money necessary to make these chemicals, add them to the product, and safely dispose of them are a waste.
• Being dangerous. The anti-microbial ingredient triclosan can lead to germs that are resistant to antibiotics, and that can kill people. I give triclosan -100 ingredient points, since it’s been banned by the FDA. Other antibacterial chemicals, such as the preservative methylchloroisothiazolinone (CMIT), get -10 ingredient points. In my view, they’re not great, but not as bad as triclosan. If were allergic to MIT, of course I’d check for that ingredient and not use any product that contains it.
• Being non-renewable. We can’t keep using up natural resources that are in limited supply, such as petroleum.
• Being dilute. Dilute “convenience” products waste resources compared to concentrated “value” products.

Ingredients that solve problems deserve positive points. For example, packaging for the simplehuman hand soap I like to buy “is made with 35% post-consumer recycled material.” That gets +1 ingredient point for closing the loop on recycling.

You’ll probably need to do a little research to decide how to award ingredient points. Check out this daunting list of soap ingredients. How many are problematic?

Water [Aqua], Sodium Methyl 2-Sulfolaurate, Cetyl Betaine, Glycerin, Cocamidopropyl Betain, Disodium 2-Sulfolaurate, Tocopheryl Acetate, Panthenol, Lauryl Betaine, Sodium Chloride, Methylchloroisothiazolinone, Methylisothiazolinone

— not so simple ingredient list for “simplehuman fragrance free liquid hand soap”

I give this list -10 ingredient points, since it contains the antibacterial preservatives methylisothiazolinone (MIT) and methylchloroisothiazolinone (CMIT); in terms of ingredients, this soap gets +1 -10 = -9 points. But it earns an overall positive sustainability score through other factors (satisfaction, affordability, packaging, etc.).

Packaging Points: What Is the Product-to-Package Ratio?

This is a fun one. Compare the weight of the product in the package to the weight of the packaging without the product. If product is…

• … more than half the package weight: up to +5 packaging points.
• … exactly half the package weight: zero packaging points.
• … less than half the package weight: down to -5 packaging points.

For example, each simplehuman liquid soap refill pack weighs 1,061 grams when full, and 32 grams when empty. My sustainability app calculates 4.6984 packaging points as follows:

1. I measured how the empty package weighs. My app determines how much product is in the package by subtracting empty from full weight: 1,061–32 = 1,029 grams of soap in each package.
2. My app divides product by package: 1,029 / 1,061 ~= 0.96984.
3. Then it multiplies by 10 to scale from 0 to 10 points, then subtracts 5 to range from -5 to +5.

For extremely fragile or light products, my app slides the scale. My point system is designed to consider all the impacts, but still leaves room for judgement and common sense.

Local Points: How Far Does It Have to Travel?

Supporting your local economy is part of sustainability. I give +5 points for soap made in my local community (which I can buy at our local farmers markets), +2 for soap made in New England (my region), 0 points for soap Made in USA, and -1 for soap made in other countries.

Composting Points: How Biodegradable Is the Packaging and Product?

In a truly sustainable economy, all products and packaging would be fully compostable and recyclable. Packaging that I can put in my backyard compost bin gets positive composting points.

Recycling Points: How Recyclable Is the Packaging and Product?

Since I can’t compost or recycle the simplehuman refill pouch (it’s flexible plastic), I give it -1 recycling points. I give zero recycling points for rigid plastic and other materials that could be recycled, but in actual fact are not. (In my next post I’ll explore, What can really be recycled?)

Along the “Water” Pathway

Soap is really is a two-part product. Unlike hand sanitizer, soap needs water to work. So exploring the water pathway is part of evaluating the sustainability of washing.

Source Points: Where Do You Get Your Water?

Tap water is more sustainable than bottled water. Liquid soap is bottled water with soap added, so I give bar soap and powdered detergents positive water pathway points.

Treatment Points: How Is Your Water Treated?

Water utilities add chlorine and fluoride to drinking water. Those chemicals are not needed for washing. Add points if you can use water that isn’t treated unnecessarily.

Efficiency Points: How Much Water Do You Use?

The less water required, the better. Give positive points to low sudsing soaps and detergents that are designed to work in high-efficiency machines. Give points for a high-efficiency sink aerator that uses less water while you wash your hands for the recommend 20 seconds.

Prevention Points: How Clean Is Your Wastewater?

Add points for products that prevent water pollution. Subtract points for any soaps or personal care cleaning products that contain polyethylene and polypropylene microbeads. or other agents that are difficult to remove from wastewater.

Diversion Points: Where Does Your Wastewater Go?

Add points if you use a greywater system for shower and washing machine effluent.

Along the “Energy” Pathway

For washing hands, energy use isn’t likely a big impact, assuming you’re making good choices along the Water pathway. But for washing clothes, you do have a choice whether to wash in cold or hot water, and that has implications for energy.

Efficiency Points: How Much Energy Do You Use?

If you can wash in cold water, you can avoid using energy. Give positive points for detergents with enzymes designed to work well in cold water. Subtract points if your hot water is so hot you can’t comfortably wash your hands for 20 seconds — water that is too hot wastes energy and deters effective hand washing.

Source Points: Where Does Your Energy Come From?

Fossil fuel is an unsustainable energy source. Give positive points if you heat water with wood or electricity from solar or other renewable energy sources.

Prevention Points: How Clean Is Your Energy?

Solar, wind and hydropower produce no pollution. Give positive points if the energy you use for washing comes from clean renewable sources.

Making Well-Informed Decisions

I realize if you had to do all of the above by hand it would be tedious. But it’s actually kind of fun to answer questions about a product and see how the sustainability app scores it.

As you answer survey questions, the app adds up points along each pathway on the fly, and combines each those pathway scores into a single sustainability score. You can use this single score, or drill down to see each pathway score, to guide your decision making.

The idea behind using a sustainability app that scores products and practices is so you can determine the relative sustainability of your options, then factor that in as you choose the best way to meet your specific needs.

If you regularly use multi-dimensional sustainable thinking (and a handy web app for sustainability to provide a quantitative score) to evaluate practices, products and services, you’ll soon be making well-informed decisions that really do make the world better for everyone.