<P> In addition to lengths of pipe or tubing, pipe fittings are used in plumbing systems, such as valves, elbows, tees, and unions . Pipe and fittings are held in place with pipe hangers and strapping . </P> <P> Plumbing fixtures are exchangeable devices using water that can be connected to a building's plumbing system . They are considered to be "fixtures", in that they are semi-permanent parts of buildings, not usually owned or maintained separately . Plumbing fixtures are seen by and designed for the end - users . Some examples of fixtures include water closets (also known as toilets), urinals, bidets, showers, bathtubs, utility and kitchen sinks, drinking fountains, ice makers, humidifiers, air washers, fountains, and eye wash stations . </P> <P> Threaded pipe joints are sealed with thread seal tape or pipe dope . Many plumbing fixtures are sealed to their mounting surfaces with plumber's putty . </P> <P> Plumbing equipment includes devices often hidden behind walls or in utility spaces which are not seen by the general public . It includes water meters, pumps, expansion tanks, back flow preventers, water filters, UV sterilization lights, water softeners, water heaters, heat exchangers, gauges, and control systems . </P>

When did they stop using copper pipes in houses