When I was a kid the only water bottles were simple white plastic with a ribbed bendy-straw that came out like the proboscis of a giant insect.  And the only people who used these water bottles were the other kindergartners who were also forced to play soccer, and needed something to wash down the orange slices and cracker jacks.  These water bottles—more cylindrical containers than bottles—beared the emblem of our soccer club, were not airtight, and most definitely were not brought to school, where things that made students more likely to need to go to the restroom were not welcomed.

The other night I was in the supermarket, and while looking for the most up-to-date version of the Oreo cookie, I came upon the water bottle aisle.  Water bottles have their own aisle now.  The bottles were in many different colors, and showed a history of technological innovation.  Adjustable nozzles.  Rubber grips.  Filters in case the bottled water that gets poured into the water bottle has too much—I don’t know—water in it.

And no longer is the basic white plastic of my soccer-playing youth the only choice.  In fact, it’s probably not a choice at all.  Today’s water bottles come in stainless steel, aluminum, high-density polyethylene, low-density polyethylene, polypropylene, and something called “copolyester,” which I had thought went out with the 1970s.  If this seems as clear as polypropylene, below is a bottle comparison chart that I pulled, for your convenience, showing the different water bottles that are sold by a company named REI so that you can tailor your purchase decision to your plastic-resistance preferences.  A 5-star rating means that the material offers the greatest resistance.

Bottle Material	Impact Resistance	Odor Resistance	Visual Clarity	Bottle Feel	Resin Code
Tritan copolyester	***	****	Clear	Rigid	7
Polyethylene (HDPE)	****	***	Cloudy	Semi-rigid	2
Polyethylene (LDPE)	****	***	Semi-opaque	Squeezable	4
Polypropylene	****	***	Semi-opaque	Rigid	5
Stainless steel	****	*****	Opaque	Rigid	N/A
Aluminum	**	*****	Opaque	Rigid	N/A

As you can see from the table above, all of the plastic bottles come with a resin code.  I don’t know the resin code for the water bottle I used back when I was standing out on a soccer field and pretending to care where the ball was kicked.  I’m sure it was chock-full of the dreaded bisphenol A (BPA), something equaled in terror by only the bubonic plague.

But selecting a material with the perfect opacity and resistance is barely half the work!  Now you must settle on a design for the mouth opening.  Here are your choices: wide mouth, narrow mouth, push-pull valve, and bite valve.  And if anyone wants my opinion, I think there should be a “fountain valve” that looks just like the spouts on the metal water fountains we all remember from school, one that you have to hunch over and really press so that your back is left vulnerable to attacks from bears or kick-me signs.

As I stood in the aisle, I thought about the kind of water bottle I would choose.  Was I a polyethylene person or more of a stainless steel person?  Did I like a water bottle that dented easily or not so easily?  What were my thoughts on resin?  Did I even know what resin was?  The Existentialists thought that free will and the purpose of life were the most difficult questions and the ones most worthy of extended study.  They would have been surprised to learn that choosing a water bottle requires far more introspection.

But if choosing a water bottle requires more work, it is because the water bottle delivers more meaning to our lives.  Our bodies are roughly 60% water—or, if you’re like me, 40% water and 20% hazelnut creamer.  And if the body is indeed a temple, then it needs a proper chalice—a chalice made of stainless steel.  Or aluminum.  Or low-density polyethylene.