# Question regarding pressure equ.

1. Apr 27, 2006

### cscott

$$\Delta P = \rho g \Delta h$$

If my water reservoir for my house is high on a hill I can calculate the pressure at the house if I know the height of the reservoir. If I cut a hole at the base of the hill and let the water spray directly up, will it always rise to the height of the reservoir? I mean, you can use the conservation of energy but I just noticed the equation worked both ways with the same values...

2. Apr 27, 2006

### civil_dude

Yes, but it is static pressure.

If the water sprays, it loses energy from entrance/exit losses as well as friction losses of any pipe and therefore never rise to the same elevation. If you were to run a pipe from the bottom of the hill up to the top of the reservoir, the water would eventually rise to the same elevation under a static condition.