Achieving the greatest cleanup efficiency with minimal footprint remains a paramount goal of the water treatment industry. Toxic organic compounds threaten drinking water safety and require effective pretreatment. Hydroxyl radicals produced by the Fenton process (Fe2+/H2O2) destroy organic contaminants based on their strong oxidation potential. An upgraded reaction using solid catalysts, referred to as the Fenton-like process, was recently adopted to avoid the ferric sludge generation during the conventional Fenton process. However, most heterogeneous Fenton-like catalysts operate optimally at pH 3-5 and quite weakly in near-neutral water bodies. Here, we evaluate the feasibility of an electrolytically localized acid compartment (referred to as the Ella process) produced by electrochemical water splitting under flow-through conditions to facilitate the Fenton-like process. The Ella process boosts the activity of an immobilized iron oxychloride catalyst >10-fold, decomposing organic pollutants at a high flow rate. The robust performance in complex water bodies further highlights the promise of this platform.