This month, you might see two young girls depicted on the side of London's buses, each hauling a jerrycan of water that is more than half their weight.
Some 748 million people around the world do not have access to safe water. That is one person in 10. It is nearly always up to girls and women to hike treacherous, winding paths to fetch water for their families, and carry that heavy burden home again.
Ze and Solo are best friends from the African island of Madagascar. This is the second in a series following them as they share with WaterAid their story of what it means to be a girl.
WEEK 2: Solo's story
One of the girls you might have seen on the buses is 13-year-old Solo.
Soloniaina Havatiana Rasoambola is the only girl among a family of 6 children, and the gruelling task of fetching the family's water falls to her each day. Her most prized possession is a doll, given to her by missionaries.
I asked her to talk us through her daily routine.
WaterAid/ Abbie Trayler-Smith
"I wake up at 5 am, it's quite dark, the sun is just rising and red and it's cold. I go to collect water as soon as I wake up. It's difficult but the water is cleaner then.
When we fetch water we try to never go alone. We knock at the doors for our friends. Some of us are just 12 or 11, some are 15 or 16.
The walk is very difficult, it's very narrow with plants all along the side of the path that are spiky and hurt our arms. I have been tripped by coarse grass on the way back. I hurt my knee and then I broke my jerry can.
Small muscles for a heavy load
"Sometimes we take a bucket, sometimes we take a jerry can. When we are tired from the field we choose the bucket as the jerry can is very heavy. We only have small muscles!
I collect water, and then I prepare our breakfast. It's hard collecting water before having breakfast but we need to have water for cooking. We have rice around 7am. We go early in the morning as our parents have to do other things, they are in a hurry to go to the field or do other work.
After that I collect wood for cooking. I go to the north part of the village looking for it. ... It's heavy, sometimes if we find a lot, it can be as heavy as a jerrycan. We really have to go slowly when we come back with it.
After this I grind the rice and prepare it for dinner.
WaterAid/ Abbie Trayler-Smith
We have boiled cassava for lunch.
Then we play - we play for a little while - then we prepare the food for dinner and then we go to bed. We play mothers, we take it in turns to have the doll.
A decision made from duty
"It was my choice to leave school. I said to my parents, 'you can go ahead and continue doing what you are doing for our living and I will stay home to do everything else.' Because for us here, it's never that everything is ready to be eaten. We need to find what we need to eat. We think it's necessary that we help our parents.
The boys sometimes help with the work in the house and for us it's preparing food, collecting water, taking care of the babies, taking care of all of the work in the house, really this is our job.
I miss school. If I could I would still go to school. As you know I am the only girl in my parents' family so I have no choice but to not go to school anymore."
The Department for International Development has agreed to match all donations received this summer for WaterAid's campaign, To Be A Girl, aiming to bring 130,000 girls safe water and basic sanitation to improve their health, their safety, their education and their future.
WaterAid/ Abbie Trayler-Smith