If you needed proof that you're never too young to care about the world, look no further than Erin. At just five years old, she has grasped that clean water is life-giving, and not everyone has it.
When asked why she's taking on the Big Walk, Erin didn't hesitate:
"I get clean water from the sink, and some of these girls are walking and walking and walking to get water and it's not even clean. That's not fair. I'm collecting money for 40 days to make sure they get clean water."
She's been clocking up the kilometres with her mum, dad and baby brother Ruairi - taking in their village, a walk past some very vocal cows, the shops, and a lake. And in true eco-warrior fashion (Erin's official title at school), she's been picking up litter along the way too.
The response from sponsors has moved her: "It's really cool that even people I don't know have been giving money. It means it's working. Thank you."
And on the scale of the challenge ahead? "It's going to be a very very very long way. But I really want to do it to give people the clean water."