Electrocoagulation technology using aluminum electrodes spaced 20 cm at a voltage of 20 volts, a current of 10 amperes for 60 minutes was proven to be able to reduce Pb in liquid waste. This electrocoagulation specification was developed with the addition of Ca(OH)2 at pH 10.5 and an activated charcoal filter with a thickness of 20 cm in order to determine the best results for reducing lead (Pb). This study was to analyze the effect of the addition of Ca(OH)2 pH 10.5, activated charcoal thickness of 20 cm and the combination of addition of Ca(OH)2 pH 10.5 and activated charcoal thickness of 20 cm. The research method used true experimental which was carried out in the laboratory with a posttest only with control group design, which was a research design consisting of a control group and an experimental group totaling 4 treatments. Data were collected from 5 experiments to obtain a lead reduction rate (Pb) and then analyzed using alpha 5%. The results showed that there was a significant difference in Pb reduction in all treatments. The most optimal reduction in Pb in the treatment of aluminum electrodes was 20 cm with the addition of 60.01% activated charcoal and the addition of Ca(OH)2 and 61.86% combination of activated charcoal. This difference in Pb reduction was shown in accordance with the Post Hoc test for all treatments in the treatment between 20 cm electrode and 20 cm electrode + activated charcoal (p-value = 0.038) and treatment between 20 cm electrode and 20 cm electrode + Ca(OH)2 + activated charcoal (p-value = 0.007). Treatments that were effective in reducing lead (Pb) were treated with 20 cm aluminum electrodes with the addition of 60.01% activated charcoal and 20 cm aluminum electrode treatments followed by the addition of a combined Ca(OH)2 and 61.86% activated charcoal. It is recommended to use electrocoagulation using aluminum electrodes spaced 20 cm at a voltage of 2-volt with a current of 10 ampere for 60 minutes followed by the addition of an activated charcoal filter with a thickness of 20 cm or the addition of a combination of Ca(OH)2 and activated charcoal.