Copper pipe and tubing is usually preferred over plastic for use in water supply systems. Copper will not corrode, is lighter than galvanized steel, and is less susceptible to leaks than plastic pipe. Most plumbers believe plastic pipes are more likely to leak because they don't fit as well. However, copper is more expensive than plastic. Plastic is easier to assemble and attach to existing metal pipe. Plastic pipes are lightweight, easy to cut, and very durable. Plastic pipes may be joined with copper pipes by using transition fittings, however, it is usually preferred to continue using copper pipe. In many cities in the United States ordinances will require using copper pipes in your home for incoming water lines because they are stronger and more durable. For more information on copper and plastic pipes, consult a home center, plumbing supply store, or plumber.