It works very well. Kellen built a rocket and then I did. Mine can get up too 100psi without breaking the seal. we have it figured that 100psi and about 12 oz of water gets up about 100 or so feet. I have yet to make a rocket that uses more than one rocket, but I know they exist(see below)
I used the tripod to (obviously) stabilize the pipe. I will try to think of a more visually appealing way of doing it.
Here is the video of the multi bottle rocket.