<P> Plumbing reached its early apex in ancient Rome, which saw the introduction of expansive systems of aqueducts, tile wastewater removal, and widespread use of lead pipes . With the Fall of Rome both water supply and sanitation stagnated--or regressed--for well over 1,000 years . Improvement was very slow, with little effective progress made until the growth of modern densely populated cities in the 1800s . During this period, public health authorities began pressing for better waste disposal systems to be installed, to prevent or control epidemics of disease . Earlier, the waste disposal system had merely consisted of collecting waste and dumping it on the ground or into a river . Eventually the development of separate, underground water and sewage systems eliminated open sewage ditches and cesspools . </P> <P> Most large cities today pipe solid wastes to sewage treatment plants in order to separate and partially purify the water, before emptying into streams or other bodies of water . For potable water use, galvanized iron piping was commonplace in the United States from the late 1800s until around 1960 . After that period, copper piping took over, first soft copper with flared fittings, then with rigid copper tubing utilizing soldered fittings . </P> <P> The use of lead for potable water declined sharply after World War II because of increased awareness of the dangers of lead poisoning . At this time, copper piping was introduced as a better and safer alternative to lead pipes . </P> <P> The major categories of plumbing systems or subsystems are: </P>

When did they stop using lead solder in plumbing