If you have galvanized steel pipes in your house, then you know the house is old. They were the standard pipes used in homes for almost a century until the use of copper piping by contractors became the standard in the 1960s and 1970s. Copper was popular because it was easy to cut, was lighter than galvanized steel pipes, and unlike galvanized steel pipes, did not rust and corrode. The most popular pipes today are made of plastic. They are even lighter than copper, are less expensive, and easier to cut. Plastic pipes come in a wide variety with a number of differences. The general rule is that polyvinyl chloride pipes and acrylonitrile butadiene styrene pipes, which are resistant to chemicals, are used for drain lines. Chlorinated polyvinyl chloride pipes are used primarily for hot and cold water supply lines.