Plumbing systems distribute potable water and remove wastewater using pipes, tubing, and fixtures. A plumber installs and repairs these systems. Historically, clay, lead, bamboo, wood, or stone pipes were used, but now plastic, copper, and lead pipes are common. In addition to straight pipes, plumbing systems require many fittings like valves, elbows, tees, and unions. Water pressure is regulated using direct-acting or pilot-operated pressure reducing valves, with smaller units made of brass. Proper plumbing provides water for uses like toilets, dishwashers, taps, showers, and cleaning.