What gauge pressure is required in the city water mains for a stream from a fire hose connected to the mains to reach a vertical height of 16.0 m?

1.57 x 10^5 Pa

Explanation:

Height, h = 16 m

acceleration due to gravity, g = 9.8 m/s^2

density of water, d = 1000 kg/m^3

gauge pressure, P = h x d x g

P = 16 x 1000 x 9.8

P = 1.57 x 10^5 Pa

Thus, the gauge pressure is 1.57 x 10^5 Pa.