The biodegradable 'Ooho Balls', which resemble large bubbles, have a jelly-like membrane made of plant and seaweed extracts.
This makes them entirely edible, though the company, Skipping Rocks Lab, says the membranes decompose after four to six weeks if not consumed.
The Ooho Balls were launched last year, quenching the thirst of consumers at special events in San Francisco and London.
Now they have partnered with a British sports drink maker to offer an alternative to plastic cups and bottles at marathons.
Oohos filled with sport drinks and gels were recently used at the Richmond Marathon in south-west London.
Runners who gave them a go seemed to enjoy the experience of putting a jelly-like Ooho in their mouth and bursting it for a mouthful of refreshment.
A common sight following marathons around the world is a mound of waste plastic bottles, used once and then discarded by runners.
Oohos could offer a solution to this, the makers say.
Oohos will now be handed out to participants at various upcoming running events to gauge their responses to plastic-free hydration.