Single-use plastic bottles have been identified as a common oceanic pollutant by the research vessel Alguita (see http://orvalguita.blogspot.com/).
Drink it once. Throw it away. That single-use bottle will be in existence for 500 years, maybe longer. Plastics break down eventually, but only into small pieces of plastic.
Take a stand, and buy a re-usable drinking bottle. Stop buying plastic-packaged soft drink, juice, water and energy drinks.
There's nothing healthy about a polluted planet with plastic-dumped seas.