Water quality and drinkability assessment are of high importance for various applications from monitoring water utilities to emergency water source evaluation. Traditionally, water quality assessment is done in laboratories with spacious and expensive equipment. We propose a wearable, mm Wave Frequency-Modulated Continuous Wave (FMCW) radar based system to assess water quality. Given its small form-factor, low price, and its robustness to lighting and weather conditions, this family of radars can be integrated into wearable devices such as smart-watches, smart glasses, smart rings, etc. Equipped with mm Wave radar sensors, such wearables enable seamless monitoring of water quality in hands free settings. The proposed system is able to directly process the In-phase and Quadrature (IQ) data generated by the radar to detect varying levels of different contaminants in four different kinds of water. Specifically, it can identify different concentrations of salt with 100% accuracy, namely nitrate and chloride, as well as detecting different types of waters including Reverse Osmosis (RO), tap, river, and well water with 99.1 % accuracy.