Present-day water-supply systems use a network of high-pressure pumps, and pipes in buildings are now made of copper, brass, plastic (particularly cross-linked polyethylene called PEX, which is estimated to be used in 60% of single-family homes), or other nontoxic material. Due to its toxicity, most cities moved away from lead water-supply piping by the 1920s in the United States, although lead pipes were approved by national plumbing codes into the 1980s, and lead was used in plumbing solder for drinking water until it was banned in 1986. Drain and vent lines are made of plastic, steel, cast-iron, or lead.
Natural and propane gas are popular inexpensive fuels for water heating needs. However, gas is dangerous and can explode. Gas water heaters have built in safety features that keep this from happening. The problem is that they 'Err' on the side of caution. See the articles on 'Pilot Lights' and 'Gas Water Heater Thermocouples' for some of the common failures.