Because they had no better materials at that time.
The Romans did not use lead. The Aquila system was a combination of aqueducts, cisterns and sewers cut through rock. These still exist and truly amazing engineering by the Romans.
That was the best material they had at that time.
That was the best material they had.
Lead (and copper).
Romans used concrete, the arch and domes which lead to roads, aqueducts, coliseums, baths, and basilicas .
Lead water pipes.
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
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.
Because that was the best material they had at that time.
They used lead pipes , which the Romans used in Rome.
The Roman had problems with lead poisoning because they made lead pipes for water supply.
Mainly lead pipes or hollowed out tree trunks. An open top aqueduct, ditches, etc was also used.
Yes and it still widely used even today