Wow! Thanks so much for the information.
Here's what I am working with ... we live out in the country in eastern washington. Our well is 1200 ft from the house, on top of a hill (about 150 ft above the house in elevation) On top of the hill, we have a deep well submersible pump (unknown horsepower) that is connected to a 120 gallon precharged tank. From there it drops down to our house. Everything currently works great. But I have been concerned that should there be a problem with the pump or well itself, we would have no reserve. To that end I thought putting in a reservoir would be prudent. Unfortunately the only place that would work for a location is at the bottom of the hill at the same elevation as the house ... we will lose our friend ... gravity.
Anyway I have access to a 1500 gal. above ground tank that I can enclose in a small building. I figured I would then move the 120 gal. pressure tank down to this building (from it's current location at the top of the hill) From there I would set up a system of valves that would allow me to route the water to the reservoir or through the pressurized tank and to the house as currently exists.
Obviously the tank will need a level control mechanism to fill it when necessary.
Anyway, I guess the question for me is: when the water comes out of the bottom of the reservoir, what should go in downstream? a pump that feeds a pressure tank? If so what sort of pump is needed? (The shallow well pump you spoke of?) A submersible pump in the tank doesn't seem like the best way to go.
Also I am uncertain about whether I need a special pump that is pressure sensitive. Obviously I want it to automatically sense whether or not it needs to be pumping.
Currently our water pressure is just fine ... though a little more wouldn't be a bad thing.
Thank you so much for the great assistance.