Disclosed herein is a liquid system tool having an integrated residual current device, RCD. The liquid system tool comprises a current circuit having a power input for receiving an alternating electrical current, AC, a rectifier for rectifying the AC into a direct current, DC, a voltage booster for increasing a DC voltage and a motor unit connected to an output of the voltage booster for driving the liquid system tool. The RCD comprises a sensor element connected to an output of the rectifier and an input of the voltage booster and being configured to collect an analog current signal and an analog to digital, A/D, converter configured to convert the analog current signal into a digital current signal. The integrated RCD further comprises a logic unit connected to the A/D converter, wherein the logic unit is configured to evaluate the digital current signal and compare it to a current requirement, and wherein if the logic unit determines that the digital current signal does not fulfill the current requirement, it is further configured to break the current circuit so that no current can flow in the liquid system tool. Also disclosed is a method for detecting residual current in a liquid system tool, and a computer program product.