Staying at a hotel on the Thai island of Koh Samui in 2015, Meghan Kerrigan noticed the four bottles of water she was given every day were clogging her trash can with plastic. Outside her door, Chaweng Beach was smothered in rubbish.

It was then that she and two friends, brothers Ryan and Matthew Kohler, had a "light-bulb moment."

"Instead of trying to solve the problem by cleaning the beaches every day, let's go to what the source of the problem is, and take the plastic bottle away," said Kerrigan, 31.