To provide a system capable of cooling spring water having pH of about 1-2, which is difficult to be handled with a simple constitution, rising a temperature over a cooling temperature of the spring water without installing a boiler, and supplying the produced hot water.

This hot water supply system includes a spring tank 10 storing the spring water and having a spring water outlet 14 at a lower section of a side wall 10a, a tube 11 disposed in a meandering state from the lower section of the side wall 10a toward a water surface of the spring water through the inside of the spring water and composed of a plastic resin to circulate the water therein, a distributing means 12 connected with the tube 11 and supplying the water into the spring tank 10 or sucking the hot water produced by being heated by the spring water, and a hot water storage tank 13 receiving the produced hot water and storing the hot water to supply the hot water.