hotwater

Hot water is water that has been heated above the surrounding temperature and is used for cleaning, sanitation, cooking, heating, and various industrial processes. In households, it is typically supplied by a dedicated water heater that makes water available at convenient tap temperatures.

Domestic hot water is produced by electric, gas, oil, or solar-powered systems. Storage tanks maintain water at a setpoint, commonly around 60°C (140°F) to limit bacterial growth, while real‑world taps are often tempered to about 50–60°C (120–140°F) for safety.

Tankless or on‑demand heaters heat water as it flows, reducing standby losses. Solar thermal systems preheat water using sun energy, sometimes combined with auxiliary heaters. Heat pump water heaters improve efficiency by extracting heat from the surrounding air.

Hot water distribution uses insulated pipes and, in larger buildings, recirculation loops to minimize wait times. Safety systems include anti‑scald valves, venting for gas heaters, expansion tanks, and periodic flushing to remove sediments and microbes.

Energy use for hot water is a major component of household consumption. Efficiency gains come from better insulation, optimized setpoints, mixing valves, heat pumps, and solar or waste heat recovery. Water heating technologies continue to evolve with climate and code changes.