Sodium hypochlorite production system and water treatment method using same

A sodium hypochlorite production system comprising:

• a raw water treatment device that treats a first sub-stream branching off from a main stream of water to be treated to obtain purified water;
• a salt water treatment device that treats saturated salt water prepared from a portion of the purified water and salt stored in a salt tank;
• an electrolyzer for electrolyzing the saturated salt water and a remaining portion of the purified water to obtain a cathode product and an anode product;
• and
• a reactor for obtaining sodium hypochlorite by making the cathode product and the anode product react each other by using a second sub-stream branching off from the main stream of the water to be treated,
• wherein the sodium hypochlorite production system does not comprise a facility to store the sodium hypochlorite produced in the reactor, and the second sub-stream branching off from the main stream of the water to be treated is not in fluid communication with a facility to store the sodium hypochlorite.