Two possible reasons, 1, A source of water and 2, in extreme cases especially during a certain dark time, the trail of witches, by use of a ducking stool.
bit too easy for my liking, i can go for the water one but the witch one a bit far fetched for me,the unlucky thing for the witches was if the drowned they we innocent but if they survived they WERE WITCHES AND THE THEY WERE BURNT AT THE STAKE,LOL,LOL.
Every village that did not have a convenient stream or river needed a pond where farm animals could drink.
No doubt communities grew in areas where their was a convenient water supply but as time passed ponds began to be dug and filled by rainwater or diverting river sources.
Apparently there are currently estimated to be about 400,000 ponds in Britain, but some three-quarters (more than a million) of Britain's ponds have been lost over the last hundred years.
Carts, wagon's wheels that were made of wood, often needed soaking with water, to stop the wheels splitting, so very often villages had large shallow puddles, maybe why.
If you look at any map you will see most cities are near a water sourse like a river. Rivers also provided power. Where there were no fast enough rivers for power, dams were used to creat ponds thus providing the power for water wheels etc.