Electrolyzed water (EW) has gained immense popularity over the last few decades as a novel broad-spectrum sanitizer. EW can be produced using tap water with table salt as the singular chemical additive. The application of EW is a sustainable and green concept and has several advantages over traditional cleaning systems including cost-effectiveness, ease of application, effective disinfection, on-the-spot production, and safety for human beings and the environment. This chapter was about the safety of the EW from the biological safety and chlorine residue two aspects, including the researches and results of oral toxicity test, the skin irritation test, the acute eye stimulation test, tub-chronic oral toxicity test and so on. EW had no effect on mouse growth as drinking water for 8 weeks and did not induce reverse mutations. Also, no effective residual chlorine after treated with EW was detected in samples. In a word, EW has no systemic effects and is safe as a sanitizer.