Well water is one of the water resources for the society. The main problem of well water is the high concentration of Fe. Adsorption using activated carbon is one of the water treatment technology. This research using well water with pH 2.26. Activated carbon is produced from cassava peel. The production process of activated carbon starting with composing cassava peel using furnace in 300⁰C for 2 hours then the activation process using KOH 0.3 N during 1 hour while stirring and heating in 50⁰C. We choose 10 mesh for the adsorbent size with independent variables in the agent of regeneration and the duration of regeneration process. The variations of the agent of regeneration are distilled water and effluent water recirculation. Whereas the durations of regeneration process are in 1 minute, 2 minutes, and 3 minutes. The highest efficiency removal of Fe in batch system obtained when the adsorbent mass 18 gram is equal to 88.3%. While in the continue system, we use adsorption column with 2.54 cm in the diameter and 80 cm in the height. At the height of 74 cm, it is equipped with overflow. The adsorption column has constant flow rate of 10 ml/minutes. The most optimum regeneration agent for cassava peel is distilled water with 3 minutes of regeneration time. It results the saturated time 119 hours, as the longest saturated time.