A liquid heater includes at least a pair of electrodes each of which having an electrically conducting surface and being spaced apart from each other. The liquid heater also includes a first heating passage defined, at least in part, by the electrically conducting surfaces of the electrodes. Electrical power to the liquid heater is provided by an electrical power supplier configured to draw an alternating electrical current having a frequency less than or substantially equal to 60 Hz and supply an alternating electrical voltage having a frequency substantially equal to or higher than 50 Hz across the electrodes. The electrodes are arranged to make electrical contacts with liquid received into the heating passage. The liquid in the heating passage generates heat when an electric current flows through the liquid and between electrodes.