Q. I’m told powdered detergents are better for my washing machine than liquid ones. Which is better environmentally?

Donnie D.
Highland Park, Ill.

A. Dearest Donnie,

Did you know that the ancient Romans used urine to clean their woolen tunics? Or that Colonial Americans boiled hog fat to add to their soaps? I mention this to point out that our clothes-cleaning arsenal has clearly evolved since those days, a good thing – but the modern choices in the laundry aisle can also be a mite overwhelming. You’ve broken it down to our two main options, powdered vs. liquid detergent, so let’s start there.

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All detergents, be they liquid or powder, contain the same basic building blocks. Those include surfactants, or dirt-busting chemicals; builders, which boost surfactants’ cleaning power; plus alkalis, enzymes, bleaches, optical brighteners, preservatives, and a bunch of other substances. We don’t necessarily know exactly what’s in which potion because companies don’t have to disclose it, making things a little tricky for us curious consumers. But you can bet all laundry detergents have some combination of the above ingredients, with varying degrees of environmental impact.

If you look at just the soap’s phase – liquid or solid – one winner does emerge from the suds, if perhaps by a small margin: powder. There are a few reasons why. One, liquid detergent is primarily water (up to 80 percent), an expensive and inefficient thing to ship around the country. It’s true that the recent boom in concentrated liquid detergents helps get around this issue, but people also tend to use a lot more of the wet stuff than they really need.

Also in powder’s corner: Its ingredients are more stable, giving it a longer shelf life and reducing the need to add funky preservatives – and making it easier to buy in bulk. It usually comes in cardboard boxes rather than plastic bottles. And liquid formulations may contain more surfactants, some of which are petroleum-based and, when they get into the water supply, can make it harder for fish to breathe.

So, Donnie, go ahead and reach for the powder scoop. Your washing machine’s specs do line up with your ecological conscience. Hooray!

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All that said, though, I think the stuff inside your soap of choice is even more important than the liquid-powder question. You want surfactants that break down quickly, reducing their impact on aquatic ecosystems, which means that you don’t want anything that contains nonylphenol ethoxylates (NPEs). These substances are toxic to aquatic life, bioaccumulative, and have been linked to reproductive and developmental issues.

Also look for soaps that use plant-based surfactants rather than petrochemicals, and no matter how much you love the scent of “ocean breeze” on your undies, it’s smart to skip fragrances. The mysterious chemical soups required to produce those pleasant smells can harm the health of both humans and water critters. Add to your wish list detergents that use enzymes and other surfactants primed to work better in cold water, which will slash the total carbon footprint of your laundry day. And finally, though I hear urine works wonders, I’d shy away from that, too.

If this sounds like a lot of homework, fear not: Others have already done a lot of the sifting for you. I’d like to point you to the gummint’s own Design for the Environment label, which identifies products whose ingredients have passed “a stringent set of health and environmental criteria,” are packaged with the earth in mind, and disclose their components to consumers. You’ll notice their list of approved detergents includes both wet and dry versions, by the way. The Environmental Working Group, as usual, has a great list of laundry products too, as does the Good Guide.

Of course, the easiest way to know exactly what’s going into your washing machine is to make the detergent yourself. I’ve used a DIY formula of washing soda, castile soap, and baking soda myself to great effect, and it doesn’t take more than a few minutes to whip up a long-lasting batch. The process might be a bit more involved than buying soap at the store – but when you compare it to, say, beating our clothes against rocks down by the river, it’s a total breeze.


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