I'm thinking outside the box on this one so please bare with me.
I have a well - the source of the water is an aquifer. A 4" pipe comes out of the ground, into a tank, through a softener system and into the house - it all works well until I loose electricity - then I have about 10 gallons of water until the power comes back on. There is a fitting at the base of the 4" pipe that allows me to divert the water when I need to work on the tank (unscrew the fitting and water pours from the pipe on its own at about 2 - 3 gallons per minute - the pump does not come on). I have been told that the well is referred to as an artesian well.
What I have thought about doing was putting a 100 gallon tank in my attic (third floor of the house) - I know that it would weigh about 900 pounds when full, but if it had a large base the weight would be distributed enough so that the joists of the attic would support it. After getting the tank in the attic I would run a line from the well to the tank and let the natural flow of water fill the tank; connect the tank to the supply line that goes into the house and I no longer need the pump (I am assuming that there would be enough pressure from the 100 gallons of water in the tank to provide pressure in the house). Can anyone tell me if this would work?

1. I doubt the artesian well would send water to a tank in your attic. Maybe, but I'd have to run a vertical pipe 15 feet up or so to find out before even starting.
2. You would have 100 gallons in your attic, but you would have next to no pressure from that. You gain about 0.4 pounds of pressure per foot of drop. Assuming a drop of 12 feet, that would be about 5 pounds of pressure. You wouldn't like that.
3. If the artesian well can send water up to that attic, then there would be no need to put a tank there. Just run the water directly from the well. But as I said, the pressure would be unsatisfactory.
4. You can spend a few hundred bucks on a gas generator and power your pump with that during times with no electricity. Much more simple answer and it bypasses the issue of having hundreds of pounds of water in your attic.
5. You might also try putting in a couple of large pressure tanks. That would give you a much larger reserve than you presently have, and not have the problem of putting a tank in the attic. It would also increase the life of your pump, since it would not have to cycle so often.

Couple of issues:

1. Your artesian well may not have enough pressure to push water all the way up to the attic without a pump assist.

2. Since the tank in the attic is not pressurized, you would have very low pressure throughout the house. In a gravity system like this the water pressure at a faucet would be dependent on the height of the water in the tank above the level of the faucet. Here are some round numbers: if you have a two story house then you have approximately 10 feet of head to the bathroom fixtures on the second floor and maybe 20 feet to the first. That means you can expect only about 5 psi of water pressure for bathrooms on the 2nd floor and perhaps 10 psi on the first. With these low vaues of pressure the shower would just dribble and your dish washer would probably not work. To put this in perspective: typical household water pressure is on the order of 45-60 psi. To get that level of water pressure you would have to place the tank 80-100 feet off the ground - that's why municipal water storage tanks are so tall.

jlisenbe and ebaines great minds think alike, and at same time almost. Good advice