Disposable plastic shopping bags are in the news again. This time it’s because the governor and state legislature of New York have overridden a local bag fee law passed by New York City. The politics of this thing are dispiriting (state legislators overriding local laws, moneyed interests pretending to be grassroots groups, etc.), but I’m going to put that aside for now and focus on a scientific claim. Many of the opponents of this law cite an old study to try and show that disposable bags are actually more environmentally friendly than reusable bags. Their campaign has succeeded enough that a commenter asked “Are re-usable grocery bags really better for the environment?” on my Money Saving Resolutions post. If bags are used in a very odd and foolish way it is possible that disposables are more efficient, but looking at how bags are actually used in the real world it is incredibly clear that reusable bags crush disposables.

How Cotton Bags Beat Disposables

So, onto the study. The finding that many disposable bag proponents like to trumpet is that you could use 327 disposable plastic bags for the same energy that it takes for a single reusable cotton bag. One big assumption behind this claim is that the study expects every single disposable plastic bag to be re-used as a trashcan liner. I know many people try and reuse them, but the bags accumulate so quickly that there are often too many to reuse them all. Think of all the closets and drawers exploding with old plastic bags (likely in your own home). Eventually there’s no more room and people throw out the extras. Some avoid this by emptying trashcans “filled” with individual used tissues, but this is pretty much the same as throwing out a bag. The study notes that if only 40% of disposable bags are reused as liners then a cotton bag equates to 173 disposables. This is still big, but it may feel more doable. In the end, though, it’s pretty dang easy to reuse a cotton bag hundreds of times. Three hundred is a big number so it seems scary and impossible, but in reality it’s hard not to achieve it.

Longer Lasting

The first thing that this study ignores is that cotton bags last a really long time. I don’t remember the exact dates I got each of my cotton bags, but I do know that I have never thrown one away. If they get messy the washing machine cleans them right up. If I washed them hundreds of times maybe they’d start to fail, but that would mean hundreds, if not thousands of uses. The only way I can really imagine one failing is if I put something sharp in it and the object cut the bag. Even in the case of slashed bags, there’s a centuries old invention called thread that can fix it right up (though I haven’t had to resort to that yet). At least one of my bags is over a decade old and based on how unworn it is I expect it’ll last many more decades. Once you start thinking about the 10 to 50 year lifetime of a cotton bag, a few hundred uses doesn’t seem so daunting.

Heavier Duty

The next thing the study misses is how one use of a cotton bag can replace multiple disposables. When I need a bag to carry something heavy, cotton bags are my first pick because they’re so big and sturdy. I’ve had disposable plastic bag handles break while holding them and it sucks. This has never happened to me with a cotton bag. The study tried to account for the sturdiness of cotton by noting that such bags contain on average 10.59 items per bag, while disposable bags only held 5.88. But, it does not take into account how the fear of tearing leads to disposable bag waste. Think about it: most grocery stores double bag heavy items, sometimes they double bag everything. A sturdy cotton bag can replace two heavy double bagged plastic bags (four total disposables) and you never have to worry about your items exploding out the bottom of it.

Actually Recyclable

In the study they note “we have assumed all bags are recycled or composted.” In 2006 this was a noble assumption, but clearly untrue. In 2017 it has become even more so. The low price of oil means that it is usually unprofitable to recycle plastic bags. Because recyclers in most states are for profit businesses, this means that most plastic bags these days that get put into recycling bins are going to the landfill. Maybe in the future, if oil prices rise again, this won’t be the case, but current projections show that this is unlikely for a while. Cotton bags, on the other hand, can be recycled the same way that cotton clothes are recycled. They can be turned into rags, insulation, carpet, and more. In 2009 only 5% of recycled clothes ended up as waste and cotton bags are nearly as recyclable. It’s unclear how much the lack of recycling of plastic bags changes the paper’s numbers, but it surely makes a worse case for disposables.

Grocery Math

With all the above considerations it becomes nearly impossible not to use a cotton bag enough to make it more efficient than disposables. If you only reuse 40% of your disposables and use cotton bags to replace double bagged disposables, it only takes 87 uses for the cotton bags to win. The numbers get even worse when you realize that disposable bags aren’t economical to recycle these days. Personally, I use my cotton bags at least once a week at the grocery store and sometimes I use them two or even three times per week. Even with vacations and leaving extra bags at home I figure I use each cotton bag at a minimum 35 times per year. Over the 10-50 year life of these bags we’re talking 350-1750 uses. This beats the 327 top end of the study easily and really crushes the more realistic 87 uses we found above.

The Too Many Bags Trap

The usual way that someone could fail to reuse a cotton bag 87 times is if they have too many. If you get lured in by every new design, you could end up with way more bags than you need1Editor: And don’t forget all those free bags you tend to accumulate as giveaways at events.. There are people out there with tens, sometimes hundreds, of bags. The extra bags just sit around unused and collect dust. Even I have fallen into this trap in the past, but luckily there is an easy way out of this common pitfall. It turns out that there are many people who could use a few more sturdy reusable bags in their lives. Say you’re giving a friend a gift and have some extra bags; why not wrap the gift in a reusable bag that they get to keep? Do this a few times and suddenly you’ll have a more reasonable number of bags, and your friends will too. If all of your friends are fully stocked, you can always give bags away to strangers through the magic of Craigslist or Freecycle. Once you pare your bag stash down to a reasonable size, simply resist the urge to acquire more and you’re set, easy peasy.

More Than Just Groceries

There is one reason why you might want to own more reusable bags than you need for shopping. You can use them to replace other items around your house for less money and a lower environmental cost. Instead of buying a bunch of hard plastic organizing bins, why not use cloth bags? Don’t buy a fancy bag to take with you as a carry-on, just use a cheap re-usable cotton bag. If you’re traveling in a car with kids, put all their stuff in a cotton bag instead of a crazy expensive diaper bag. Use cloth bags to help pack things when moving. All of these uses save money by replacing more expensive items and increase the utilization of the bags you already have for grocery shopping, making them pay back even faster.

What About Other Types of Reusable Bags?

So far we’ve only talked about cotton but there are many types of reusable bags. Cotton bags get mentioned in stories that attack reusable bags because they take more uses than others before they pay back. In reality, though, most reusable bags sold at grocery stores now are nonwoven polypropelene. The study found that you only need to use such bags 26 times before they pay themselves back (just 14 times if only 40% of disposable bags get reused). Personally, most of my bags are of this type and they work great. They hold more than disposable bags, but aren’t quite as sturdy as cotton. I’ve actually had a couple rip over time, but even the worst bag lasted multiple years and hundreds of uses. I currently use mostly nonwoven polypropelene bags with one or two cotton bags for very heavy items. It is probably more efficient to use nonwoven poly bags for heavy things and just let them rip every few years, but since I expect to get thousands of uses out of my cotton bags they’re pretty close.

Reusable Bags Crush Disposables

In the end, any reusable bag that gets used regularly is more efficient than disposables. Cotton bags need 100-400 uses to win, but they should be good for over 1,000 uses. Nonwoven polypropelene bags only need to be used 10-30 times to win, though they may only last a few hundred uses. If you have so many bags that they’re gathering dust, give some away to increase your efficiency. If you keep forgetting your bags at home, look into compact travel bags like the ChicoBag. Just whatever you do, don’t be fooled into thinking that disposable bags are somehow more efficient than reusables; they aren’t.

How about you? Have you ever had to throw away a reusable bag? How many uses did you get before you did? Let me know in the comments.

Profit Greenly

Environmental Blogger at Rampant Discourse

Earnest pragmatist. Non-theist ascetic. Data aficionado. Matt is a new father who's spent too much time debating whether the plastic box his spinach came in is the perfect first birthday present for his baby, or just a good one.