In Hinduism people have this belief that soul reincarnates again and again on earth until it attain the perfection and then it reunites with its source the ‘Supreme’, this is also known as way to Moksha.
There is also a shlok in Gita about it.
वासांसि जीर्णानि यथा विहाय नवानि गृह्णाति नरोऽपराणि।
तथा शरीराणि विहाय जीर्णान्यन्यानि संयाति नवानि देही।।
Meaning :- As a man discards old cloths and wears new cloths, the same way soul also discards old bodies and wears new ones.
In India people have this belief that if they serve water to thirsty they will improve their Karma and will move towards Moksha. You will find many of these kinds of pyaus all around in India where you will generally see old people serving water to the thirsty. They also believe that by doing this they will get blessings and have a better next Life.
Once on a Sunday afternoon me and one of my friend we were just wandering around in Kishanpol Market, Jaipur and he got thirsty. He saw this pyau nearby and went to fetch some water. That day I was bit blue, I saw this old lady sitting inside a small pyau and giving free water to the thirsty people and in return expecting that she will have a better next life by doing this. Her belief on Karma gave me something to think and I took this pic.