I randomly happened upon this new way of preparing waters bottles before you throw them away that saves space. I’ve never seen anyone else do this though I doubt it hasn’t been thought of before.
Allow me to demonstrate.
First, take your bottle of water that wastes your valuable space.
Good. Now take off the cap and empty (read: drink) the contents.
Now crush the water bottle like you would a can of beer (or coke).
Then put the cap on it and you’re done.
And voila, you have trash that is less trashy and takes up less space.
~Wald