Water systems of ancient times relied on gravity for the supply of water, using pipes or channels usually made of clay, lead, bamboo, wood, or stone. Hollowed wooden logs wrapped in steel banding were used for plumbing pipes, particularly water mains. Logs were used for water distribution in England close to 500 years ago. US cities began using hollowed logs in the late 1700s through the 1800s. Today, most plumbing supply pipe is made out of steel, copper, and plastic; most waste (also known as "soil") out of steel, copper, plastic, and cast iron.
Most plumbers, pipefitters, and steamfitters learn their trade through a 4- or 5-year apprenticeship. Apprentices typically receive 2,000 hours of paid on-the-job training, as well as some classroom instruction, each year. In the classroom, apprentices learn safety, local plumbing codes and regulations, and blueprint reading. They also study mathematics, applied physics, and chemistry. Apprenticeship programs are offered by unions and businesses. Although most workers enter apprenticeships directly, some start out as helpers. The Home Builders Institute offers a pre-apprenticeship training program in plumbing and other trades.