Paul__B:
The "touch lamps" operate by sensing capacitance against the mains - 110 or 240V. The "ground" side of the detector is actually the full mains voltage so that the capacitance of a person touching it provides a capacitive coupling to the actual ground. I do not think he wishes to connect his bottle to the mains.
This is what happened to me. I developed the code on an Arduino Uno, tested it on a Tiny85 with ISP programmer...it all worked perfectly.
Then as soon as I switched to battery power it stopped working. It took me a while to figure out why, ie. until then I'd always had a USB cable connected to the device and my PC was forming part of the system.
The difference in capacitance was easy to measure when it's on USB - it can actually detect a hand from a few inches away. Without the USB cable the difference drops to almost nothing. I had to go from 1MHz to 8Mhz clock to be able to measure it.