Nowadays, priming the pump, usually means "...to do something in order to make something succeed, especially to spend money."
I was reading my sisters' blog,"The Hydrant is running," about a hydrant we had next to the house when we were kids. It was nice to be able to turn a handle and get water whenever we wanted it. Howsomeever, it wasn't always that way.
Most places we lived when I was a baby didn't have hydrants; they had water pumps that were pumped by hand. If we wanted water, we took a bucket and held it under the spout and pumped the pump by hand. That was fine for us since, much of the time we didn't have running water inside the house.
Here is a picture of a water pump.
There was more to getting water with a hand pump than just grabbing the handle and pumping. The second thing we learned about pumping water was keeping a water bucket filled with water right next to the pump all the time. When you got your water, you always, also, filled up the pump bucket that always sat right next to the pump.
Why, you ax, is that? Well, like I said, you didn't just grab the handle and start pumping. First you had to "prime the pump."
After you are finished pumping your water and filling your water bucket, the water that is left in the pump runs back down into the pipe below the pump. Sometimes it drops just a little way and sometimes it drops quite a ways down toward the water level. When that happens, there is a space with only air. Hand pumps are great but they won't pump air.
To get the water started pumping up, water has to be poured into the top of the pump until all the air is displaced. Then and only then will the water be pumped to the top.
I must say, though, water always tasted better coming from a well that had a hand pump. It was always cool and always tasted absolutely wonderful. If I had one now, I might actually agree that that water put into a bottle and sealed might actually be worth paying for!
And that, children, is "Priming the Pump!"
Oh yes, there is something else I wish to mention. There is an old song from the 30s called, "Playmate." In the song there is a line that says,"Shout down my rain barrel..."
I wonder how many of us know what a rainbarrel is.
FYI: It is a barrel used to catch rain to be used for washing clothes, taking baths and etc, etc and, by the way, etc.- saving the pump water for drinking and cooking. So There! Now you know the rest of the story!