Sunday's Harrow Half Marathon won't offer water in plastic cups or bottles, instead providing hydration in biodegradable sachets made of seaweed.
Called Ooho, the little water bags are biodegradable in four to six weeks and even edible – runners can just nip the corner off, sip the filtered water inside and eat the rest. They're made by London start-up Skipping Rocks Lab who says its seaweed material is actually cheaper than plastic and can be used for soft drinks, spirits and cosmetics (but maybe don't eat those ones).
Reusable water bottles will also be available at the 13.1 mile race in north-west London, taking place on September 16th.
The organiser of the Harrow Half Marathon says this will be London's first event to be free of single-use plastic water bottles.