Yes it's wasteful. Do what I did, save yourself the money and start making your own water, it's extremely easy and costs next to nothing. Check out https://www.tinkercoffee.com/blog/2017/11/9/thats-some-high-quality-h20
Coffee
☕ - The hot beverage that powers the world!
Coffee gadgets - It's always great to learn about new gadgets. Please share your favorite hardware or full setups. It might inspire newcomers to experiment!
Local businesses - Please promote your local businesses. If you are not the owner of the business you are promoting, kindly ask the owner if it's okay. It would be great if the business has a physical store to include an exterior or interior shot.
There's also the "pavlis" recipe, or simply the potassium bicarbonate mix:
Make a concentrate of 10 grams per 100 mL, then use 1ml of concentrate per 1 liter.
Be sure to keep the concentrate in the fridge to slow down the growth of any civilizations, though. A 100ml batch lasts me about 6 weeks at roughly 4 shots a day.
I don't know what minerals they place in the packets exactly, but some salts tend to be very sensitive to moisture and attract moisture from the atmosphere (more so than sugar or table salt). Kept in a paper satchel, which is permeable to moisture, they could potentially absorb enough moisture to become a wet goopy mess in a paper packet. So my guess is that they use plastic for stability reasons of their mix. Sure, they could sell it in glass jars with a measuring spoon, I guess.
This thread is a new rabbit hole for me to go down.