Wouldn't the storage tank & 10W
pump combination be the more brilliant invention?
I've extolled the virtues of an elevated tank delivering gravity
water for many years. Not everyone has enough elevation to make it
sensible. A tank on a wooden platform delivers very low pressure. It
takes 2.1 feet elevation to create one psi at the faucet or
showerhead. A wooden platform for a water tank must be very strong
and sit upon a good footing.
Regarding the compressed air pump, I always think of energy in and
energy out. What creates the compressed air? What is the source and
what is the cost? I suppose to evaluate the efficiency one would need
to compare some other pump cost per thousand gallons, say, and the
compressed air pump energy source the same.
My cousin who built the elegant log cabin had as his first water
source a twelve-volt pump lifting water to a tank up the hill from a
small spring. The pump was energized by a battery charger. So it
still required electricity. I don't know if he ever calculated the
cost-per-gallon of pumping that way. I do know that he later had a
well dug and a normal deep pump installed.