How high would water rise in the essentially open pipes of a building if the water pressure gauge shows the pressure at the ground floor to be $270 \mathrm{kPa}$ (about $40 \mathrm{lb} / \mathrm{in}^{2}$.)?
Water pressure gauges read the excess pressure just due to the water, that is, the difference between the absolute pressure in the water and the pressure of the atmosphere. The water pressure at the bottom of the highest column that can be supported is $270 \mathrm{kPa}$. Therefore, $P=\rho_{w} p h$ gives
$$
h=\frac{P}{\rho_{w} g}=\frac{2.70 \times 10^{5} \mathrm{~N} / \mathrm{m}^{2}}{\left(1000 \mathrm{~kg} / \mathrm{m}^{3}\right)\left(9.81 \mathrm{~m} / \mathrm{s}^{2}\right)}=27.5 \mathrm{~m}
$$