A system for treating water comprising: an electrochemical cell having an inlet and an outlet, the inlet of the electrochemical cell fluidly connectable to a source of water comprising at least one contaminant, the electrochemical cell comprising: a cathode comprising a catalytic material for electrochemical generation of persulfate free radicals, wherein the cathode catalytic material comprises a metal selected from the group consisting of iron, copper, nickel, cobalt, and metal alloys; and an anode; a source of a persulfate positioned upstream of the electrochemical cell and fluidly connectable to the source of water ; a first contaminant concentration sensor positioned upstream of the electrochemical cell and fluidly connectable to the source of water ; and a controller operatively coupled to receive one or more input signals from at least the first contaminant concentration sensor , the controller operable to generate a control signal that regulates at least a rate of introduction of water from the source of water , a rate of persulfate introduction to the source of water , and a potential applied to the electrochemical cell based on the one or more input signals, characterised in that there further comprises a second water flow rate sensor positioned downstream of the electrochemical cell , and wherein the controller is further operable to receive at least one input signal from the second water flow rate sensor to generate a control signal that regulates at least the rate of introduction of water from the source of water , the rate of persulfate introduction to the source of water , and the potential applied to the electrochemical cell . an electrochemical cell having an inlet and an outlet, the inlet of the electrochemical cell fluidly connectable to a source of water comprising at least one contaminant, the electrochemical cell comprising: a cathode comprising a catalytic material for electrochemical generation of persulfate free radicals, wherein the cathode catalytic material comprises a metal selected from the group consisting of iron, copper, nickel, cobalt, and metal alloys; and an anode; a cathode comprising a catalytic material for electrochemical generation of persulfate free radicals, wherein the cathode catalytic material comprises a metal selected from the group consisting of iron, copper, nickel, cobalt, and metal alloys; and an anode; a source of a persulfate positioned upstream of the electrochemical cell and fluidly connectable to the source of water ; a first contaminant concentration sensor positioned upstream of the electrochemical cell and fluidly connectable to the source of water ; and a controller operatively coupled to receive one or more input signals from at least the first contaminant concentration sensor , the controller operable to generate a control signal that regulates at least a rate of introduction of water from the source of water , a rate of persulfate introduction to the source of water , and a potential applied to the electrochemical cell based on the one or more input signals, characterised in that there further comprises a second water flow rate sensor positioned downstream of the electrochemical cell , and wherein the controller is further operable to receive at least one input signal from the second water flow rate sensor to generate a control signal that regulates at least the rate of introduction of water from the source of water , the rate of persulfate introduction to the source of water , and the potential applied to the electrochemical cell . <EOS>