i dunno Burnt, when i was practicing "being quiet", i lost quite a bit of sample pouring it back and forth (from bottle to sample cup and vice versa), thats why i recommend water. I guess it depends on how much you are gonna practice. You can also practice while you are waiting for your QF to arrive.

I didn't need to be quiet in the private bathroom I was in, the fan was on and the guy was in the other room.. but i was prepared