Water electrolysis system

A water electrolysis system, comprising:

• a water electrolysis stack configured to electrolyze water and generate hydrogen;
• a dehumidification device configured to adsorb and remove moisture contained in the hydrogen generated by the water electrolysis stack;
• a wet line configured to supply the hydrogen generated by the water electrolysis stack to the dehumidification device;
• a compression device configured to gradually increase pressure of the hydrogen whose moisture is removed in the dehumidification device;
• and
• a purge line configured to take out a part of the hydrogen whose pressure is being increased in the compression device, allowing the part of the hydrogen to pass through the dehumidification device, and returning the part of the hydrogen to the wet line, wherein
• a liquid discharge device is provided on the wet line and is configured to discharge liquid from the wet line, and
• the purge line allows the part of the hydrogen whose pressure is increased in the compression device to join the wet line between the water electrolysis stack and the liquid discharge device.