Plumbers assemble, install and maintain piping for medical gas, water, sewage, and drainage systems. They also install the fixtures and equipment associated with these systems. Equipment such as toilets, sinks, drinking fountains, water heaters, and pumps. Plumbers are trained a variety of skills to install piping systems. They use both hand and power tools in their work of cutting, bending and threading pipes, as well as making soldered and brazed joints. Plumbers must also run tests on their installations to assure that these systems are functioning properly and meet the plumbing code. They are often called upon to clear pipe lines and drains and make repairs.