Hydraulophone in concert

so it's just a midi controller, yes? If so, the sound really isn't created by water ... merely actuated by water.

The sound originates as turbulence in water, so its similar to an aerophone but with water instead of air, so its not an electrophone. In fact it doesn't fit into any Horbostel Sachs category! Some hydraulophones are electrically amplified, and some can be run through effects like electric guitar, and yes, you can even run them through a MIDI effector and therefore use them as MIDI controller, but that adds extra to the cost (requires add-on).

too messy

Umm, I'm pretty sure the sound is being made by the air. If you know what I mean...

I wonder if it would sound different if it flowed with pee instead of water.

No it would not, the density of the liquid is the same.

Plus it's an awful joke.

@Gilleece666 i agree

@hwoods01 i agree

2:37 look the girl with glasses! she can't believe it