Help needed, fluid dynamics

1. The problem statement, all variables and given/known data

There is a building with 3 floors: ground floor, first floor and second floor. Ground floor is at level zero, first floor is 3 meters above it and second floor is 6 meters above the ground level.

The hydraulic system is made in a way that water barely reaches the second floor.

Now I let water run from a washbasin situated on the ground floor: estimate the speed of the water.


2. Relevant equations



3. The attempt at a solution

I have too many ideas (which is like having none), so I would prefer someone directing me on the right way :)

Thanks :)

 

I was thinking of considering the whole thing like a big container of water, with the top of it open and with the water level stuck at the level of the second floor. Then letting the water run from the washbasin at the ground floor could be like making a hole on the container.... it's the more reasonable idea I've come up to, nothing better...