A copper fountain at the local garden centre. I love it.
Five shiny copper cups, overflowing into one another.
You wonder what will happen when it’s all run away. You’ll have no water! You’ll thirst, and your fountain will be broken. Oh no!
You look again, and realise that it won’t. The water from one cup will fill another, and when it reaches the bottom it will be pumped back to the top, and begin all over again. It’s never going to run out. You have an endless supply.
Your thirst will always be quenched, and your fountain will continue to sparkle and splash for as long as you want it to.