I had here many tests and from many different setups
I had tap water at 220 volts dc starting at 10 amps and than when it boil (1 minute) it than goes down to 2 or 2,5 amps. Using tap water and distilled water however distilled made much more hydrogen before boil and took about 1 minute more. The two plates were 20x10 about 1 cm far away from each other. Changing the distance didn't change much. The container had 4 liters of water and consumed about 1 liter every 15 minutes.
At low voltage about 1,4 volts and using sodium hydroxide i got up to 20 amps with my resonant scheme and water didn't heat up not even a little. However the wire heated up a lot and also the resonant capacitors. Voltage was about 300v with that conditions starting from 12v battery.