Determine the minimum gauge pressure needed in the water pipe leading into a building if water is to come out of a faucet on the fourteenth floor, 44 m above that pipe.

The minimum amount of pressure needed is the difference in hydrostatic pressure at h=0m and at h=44m. 
This difference can be calculated using following formula:

Where is the density of the fluid, g is the gravitational acceleration, and is the height difference. 
The density of water is:

In our case is 44m. When we plug in the numbers we get: