Guppyfriend Washing Bag Review: Does it Really Work?

November 7, 2021

Guppyfriend washing bag with the box for the bag on top

Every time we wash synthetic clothing, tiny plastic fibers break off and enter our waterways. Researchers are still studying the impact of microplastics, but it’s safe to say that their impact is probably not good.

The Guppyfriend bag was created by the NGO Stop! Micro Waste to tackle this problem. In this post, I’ll explain how the Guppyfriend bag works and discuss whether or not it’s worth buying.

This post contains affiliate links, meaning I may earn a small commission on any purchases at no extra cost to you. This income helps me keep my blog running, and your support is much appreciated!

How Does the Guppyfriend Bag Work?

To use the Guppyfriend bag, fill it up to 2/3 of the way with your synthetic clothing. This is to allow the clothes to move freely in the bag and be washed properly.

Some of the most popular synthetic materials include:

  • Polyester
  • Nylon
  • Acrylic
  • Spandex
  • Viscose/rayon (semi-synthetic)

a clothing composition label that reads "86% polyester, 14% spandex"

If you want, you can also include clothing made from natural fibers like cotton. The Guppyfriend bag not only filters out microplastics, but also protects clothing from breaking down in the wash.

When I do laundry, I don’t usually put natural fiber clothing in the bag, but I do include them in the load to balance out the Guppyfriend bag (so it’s not just the bag bouncing around the wash). You could also add a second Guppyfriend bag to balance the load.

From there, you can wash as normal, though Guppyfriend recommends using a natural liquid detergent and using temperatures below 40 degrees celsius. I personally wash on cold or cool water and use Tru Earth laundry strips. They’re not a liquid detergent, but they’ve worked well for me with the Guppyfriend bag, and I like how they’re super portable. Keep in mind that detergent pods often release microplastics themselves, so avoid them if possible.

the washing machine load with the Guppyfriend bag and towels on top

After the laundry cycle is done, remove the clothing from the Guppyfriend bag, and air dry if possible. Using a dryer only leads to more microfiber loss. Air drying also helps make your clothes last longer, and luckily, synthetics usually dry super quickly!

If you do use a dryer, that’s totally fine too. Just don’t put the Guppyfriend bag in there—it’s not built for the high heat.

Once you remove the clothing from the bag, you should see microfibers along the seams and corners. You’ll then be able to gather the fibers into clumps and throw them in the trash—preferrably in a closed container so they don’t blow away. There’s unfortunately not a better way to dispose of them yet, as you can’t recycle or compost them.

At the end of its life, you Stop! Micro Waste says that you can recycle the Guppyfriend bag since it’s made from polyamide (just take off the metal zipper). This bag itself is synthetic, which seems counterproductive, but it doesn’t shed microplastics itself because it’s made of monofilaments, which are “more like stable sticks than threads” according to the Guppyfriend site.

Results After Using the Guppyfriend Bag

a clump of microfibers on my fingertip

I’ve been using the Guppyfriend bag for about 2 months (8 washes) now. After each wash, I usually find fibers on the outside of the bag, likely from my other clothing in the load. Inside the bag, there are usually fewer fibers, but they tend to gather around and seams and corners. I can usually gather a small clump after a couple washes.

My clothes have gotten clean, and I haven’t had any issues with the bag so far. I’ll update this post over time with any longevity observations.

According to independent tests done by the German Textile Research Centre North-West, Fraunhofer Institute, and University of California at Santa Barbara, the Guppyfriend bag retains 90% of microfibers that break off in the wash. It actually even reduces the amount of fiber breakage by 79-86% in the first place.

microfibers gathered on the outside of the Guppyfriend bag near the seams

Do You Need a Guppyfriend Bag?

I used to be pretty skeptical of the Guppyfriend bag since it seemed counterproductive to get a synthetic bag to prevent microplastic polluation. Does the production of the bag offset the relatively small volume of fibers it will catch in its lifetime? Don’t get me wrong, microfibers are tiny, so you will be capturing millions of them over time (more than 700,000 fibers are released in a single load of laundry). I’m just talking about the amount of waste captured vs. created.

It’s estimated that only 9% of plastic ever created has been recycled, so it makes me wonder whether the Guppyfriend bag will be recycled, and whether local recycling plants take them since it doesn’t seem like a traditional “hard” plastic.

But, at the same time, the Guppyfriend bag does reduce fiber breakage significantly. So, you may ultimately be reducing waste since your clothes will last longer. If you’re only concerned about protecting your clothing though, you could use a pillowcase for a similar effect (but it won’t filter out microfibers).

I ultimately decided to get one because I have a significant amount of synthetic clothing as a runner. At least 50% of my laundry loads are synthetic since I don’t wash my street clothes as often. Washing your clothes less often reduces microfibers the most, but that’s unfortunately not possible for sweaty workout clothes.

If you don’t have as much synthetic clothing, I’m not sure that getting a Guppyfriend bag is a net positive—I’d love to see life cycle assessments on the Guppyfriend bag to figure out the impact based on how long you use the bag, what you put in it, and what happens if the bag can or can’t be recycled. We’d also need to understand how harmful microfibers really are.

Based on my experience, the Guppyfriend bag does work, so I would recommend it if that was your main concern. I just wanted to be transparent and include a discussion of the broader impact, which is still not 100% clear.

the Guppyfriend bag filled halfway

Where to Buy the Guppyfriend Bag

If you’re looking to buy a Guppyfriend bag, it would mean a lot if you used my affiliate links below at sustainable brands or more conscious retailers (if you can, shopping local is also great!). The bag is a pretty similar price ($35) at most places.

  • Patagonia
  • REI
  • Organic Basics (use code LILYOBX for 10% off). Carbon-neutral shipping from Denmark (ships internationally, but most local to folks in the EU).


If you’ve used the Guppyfriend bag, let us know your experience in the comments. Regardless of whether you get one or not, thanks for being conscious of your environmental impact!




  • Nina | Lemons and Luggage November 9, 2021 at 2:11 pm

    I hadn’t heard of this particular brand but of similar products. Thanks a lot for the honest description. It’s good to know some of the less ideal things about it as well so we can make an informed decision before possibly buying a product like this.

    • Lily November 10, 2021 at 8:52 am

      No problem, Nina! Yeah, I think the main thing is that we really just don’t know a lot about microplastics yet, and it’s impossible to do good longitudinal studies since everything is already polluted. I hope we know more about them soon though!

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    I'm Lily, and I run races and go places (& blog about it). I also try to advocate for the planet & its people.
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