As with other construction workers, employment of plumbers, pipefitters, and steamfitters is sensitive to fluctuations in the economy. On the one hand, workers may experience periods of unemployment when the overall level of construction falls. On the other hand, shortages of workers may occur in some areas during peak periods of building activity.
Plumbing originated during ancient civilizations such as the Greek, Roman, Persian, Indian, and Chinese cities as they developed public baths and needed to provide potable water and wastewater removal, for larger numbers of people. Standardized earthen plumbing pipes with broad flanges making use of asphalt for preventing leakages appeared in the urban settlements of the Indus Valley Civilization by 2700 BC. The Romans used lead pipe inscriptions to prevent water theft. The word "plumber" dates from the Roman Empire. The Latin for lead is plumbum. Roman roofs used lead in conduits and drain pipes and some were also covered with lead. Lead was also used for piping and for making baths.