The invention provides a heater arrangement and method for heating a liquid, wherein the heater comprises a heating element, wherein the method comprises (i) heating the liquid in the heater wherein the heating element is in contact with the liquid, and (ii) applying a potential difference between the heating element and a counter electrode, wherein the potential difference has an AC component whereby the potential difference varies with an AC frequency in the range of 0.01-100 Hz and wherein the potential difference is applied with a cycle time, wherein the potential difference has a sign during a first part of the cycle time that is opposite of the sign of the potential difference during a second part of the cycle time, and wherein during one or more of the first part of the cycle time and the second part of the cycle time, the potential difference temporarily changes sign.