Tap water

Tap water is water delivered to buildings through plumbing from a public or local distribution system. Its quality depends on its source, treatment, and the condition of the distribution pipes.

Drinking water treatment: Processes that remove or inactivate contaminants in water to make it suitable for drinking. Treatment prepares source water before it enters the distribution system.
Surface water: Water found in rivers, lakes, reservoirs, and other bodies at Earth’s surface. Many public systems draw tap-water supplies from these exposed sources.
Drinking water: Water intended for human consumption, including water used for drinking and food preparation. Tap water is a widely distributed source of drinking water.
Lead contamination in drinking water: The presence of lead in water, often caused by corrosion of lead-bearing plumbing materials. Lead can enter tap water after treatment as it passes through service lines or building pipes.
Bottled water: Water packaged in sealed containers for drinking or other uses. It is purchased in containers rather than delivered through a building’s plumbing.
Water distribution system: Pipes, pumps, tanks, and related infrastructure that carry water from treatment facilities to users. This network delivers treated water to buildings and maintains pressure.
Groundwater: Water stored beneath Earth’s surface in saturated soil and rock. Wells and aquifers supply many local and municipal drinking-water systems.
Water fluoridation: Adjustment of fluoride concentration in a public water supply to reduce tooth decay. Some utilities add fluoride to tap water as a population-level dental-health measure.
Legionella: A genus of bacteria that can cause Legionnaires’ disease and proliferate in certain water systems. Building plumbing conditions can allow growth even when incoming tap water is treated.
Private water supply: A drinking-water source not managed as a public utility, such as an individually owned well. Private supplies may lack the routine monitoring applied to regulated public systems.

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Mineral waterCompared with: Tap water may contain minerals too, but its source and regulatory category differ from bottled mineral water.