Does rewashing Ziploc bags really save money?

It may save you money, but is washing and reusing Ziploc bags an effective use of your time? Let the calculations begin!

Mal writes in:

I loved your post about how little you save by not flushing. You should do the same thing about your favorite bugaboo, rewashing Ziploc bags!

Rewashing Ziploc sandwich bags is something that I’ve joked about being a frugality “step too far” since the first days of The Simple Dollar. In March 2009, I completely prepared a post on this very topic, intending to present it in a very tongue-in-cheek fashion on April 1, 2009, but I never got around to posting it. Why? It simply read too close to being serious, as though I were strongly advocating rewashing Ziploc sandwich bags as a method to become a millionaire.

However, I did do some real research into the topic to find out how much a person could actually save by rewashing Ziploc sandwich bags. Here’s what I learned.

First of all, in experiments in our own dishwasher, you can wash and re-use a single Ziploc sandwich bag seven times, for a total of eight uses, on average. I would test this by seeing whether or not the sandwich bag would hold liquid after a thorough cleaning. I tried several bags, with use counts ranging from two uses up to one bag that managed nineteen uses. The average, however, was eight uses per bag.

I also timed how long it took to handle each individual bag to properly clean and dry it. In order to get it clean and also get it appropriately dry, you have to pre-rinse the bag a bit, then carefully spread it across as many dishwasher tines as it will fit around. With some practice, I was able to get this procedure down to about twenty seconds a bag.

How much water and detergent is used to wash a bag? I could fit eight bags on the top rack of our dishwasher. According to my calculations, the cost to run a full load is 15.6 cents worth of detergent and water. This means each bag uses 0.9 cents’ worth of detergent and water to get clean.

How much do such Ziploc sandwich bags cost? You can get 500 Ziploc sandwich bags for $8.38 at my local Sam’s Club. This calculates out to a price of – get this – 1.7 cents per bag.

It’s not going to be good, is it? Let’s run the calculations and figure out the savings.

Over eight uses of a Ziploc sandwich bag, you can either buy eight new ones at a cost of 1.7 cents per bag, for a total cost of 13.6 cents, or you can use one bag (cost: 1.7 cents), wash it seven times (cost: 0.9 cents per wash for a total of 6.3 cents), giving a total cost of 8.0 cents, and spend two minutes and twenty seconds rinsing and positioning the bags so that they actually get clean.

You could repeat all of this 25.7 times in an hour, so let’s look at the final math.

You could either use 206 new Ziploc sandwich bags at a cost of $3.50 or you could use 26 new sandwich bags at a cost of 44 cents, wash each one seven times in the dishwasher (at a cost of 0.9 cents per wash, a total of $1.64), and spend an hour doing it.

Your total savings for an hour of washing Ziploc sandwich bags is $1.42.

That, to me, is not worth it. Given the multitude of things a person can do for an hour to earn a return better than $1.42, to spend your time washing Ziploc sandwich bags just to save that small amount is a true waste of time.

Sure, a person with very strong environmental beliefs might choose to do so. Of course, if you have strong environmental standards, why are you using Ziplocs in the first place? Use some heavy-duty reusable containers.

The moral of the story is this: washing Ziploc sandwich bags is not an effective use of your time. It’s an activity that earns $1.42 per hour of nonstop baggie washing. That’s simply not worth it.

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