Galvanized steel pipe mainly used in transmission of coal gas, steam. It was used as water pipe, but after several years past, there were many rust in the pipe, and water get yellow color for carrying iron oxide. The water not only polluted dishes or other sanitary ware, but also carrying bacteria produced in the internal surface which not smooth . As a result of the corrosion, the water contains heavy metal element is too much and is harmful to people’s health.  For this reason, developed countries gradually banned it using as water pipe since 1960s.