The magnesium rod in the electric water heater is used to react chemically with the scale, so that the scale generated by heating in the water heater will not form a hard block and be wrapped on the heating rod. After a long time, the magnesium rods inside will be consumed. Generally, it takes about 2 years to open the sealing mouth of the water heater and check the condition of the magnesium rod. If the magnesium rod has not been consumed, its surface has formed a pitted state, resulting in a large number of flocs. At this time, it is necessary to scrape off the metallic luster of its surface with emery cloth or sharp knife to play a role. If the magnesium rod is used up, it should be replaced in time, otherwise the surface of the heating tube in the water heater will soon be surrounded by scale, which will cause the heat to be unable to dissipate into the water, thus increasing the temperature of the heating rod and shortening its life.