Certain Acid and Chemical wastes and Older domestic water mains
lead
Lead was used by plumbers in ancient Rome for water pipes because it was malleable and easy to work with. However, prolonged exposure to lead can lead to health issues, including poisoning.
lead
If you refer to the composition, it is Lead (Latin: 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" -Wikipedia
Lead (and copper).
They used lead pipes , which the Romans used in Rome.
Mainly lead pipes or hollowed out tree trunks. An open top aqueduct, ditches, etc was also used.
At the time of the Roman Empire, the Romans used pipes made of lead, because it is a cheap metal that is easily worked into pipes, and which unlike iron doesn't rust. The Romans didn't worry about lead poisoning. Lead pipes continued to be used even into the mid 20th century, before we became more concerned about the danger of lead poisoning.
Copper pipes are now most commonly used in plumbing. Lead pipes were used long ago, and the word plumbing is derived from the Latin word for lead (plumbum). Iron pipes were used until relatively inexpensive copper pipes became readily available during the twentieth century.
Plumbers in Rome historically used lead in their pipes. Lead pipes were commonly used in ancient Rome due to their malleability and ease of installation, however, it was later discovered that lead could leach into the water supply and pose health risks.
Lead,
it's used in plumbing and pipes.