What does stormwater mean?
Stormwater is water that results from rain, snowmelt, or similar precipitation and then flows over surfaces or through drainage infrastructure. In everyday discussion it often means runoff entering streets, drains, streams, or other waterways, especially when heavy rain has overwhelmed a local drainage system. In civil engineering, environmental management, and urban planning, it can also denote the systems and processes used to collect, treat, store, or discharge this water. The term became especially prominent as cities developed extensive impervious surfaces such as roads and buildings, which prevent rainwater from soaking into the ground and increase runoff. Modern stormwater management therefore commonly focuses on reducing flooding, limiting pollution, and protecting nearby rivers and groundwater. The word is most often used in technical, municipal, environmental, or construction contexts rather than in casual conversation.
Water that flows over the ground or through drainage systems as a result of rain, snowmelt, or other precipitation.
"The storm dumped so much stormwater that several low-lying roads were flooded."
Usually uncountable, though “stormwaters” can refer to distinct bodies or flows of runoff in technical writing.
Infrastructure or a drainage network used to collect, convey, treat, or discharge precipitation runoff.
"Engineers replaced the aging stormwater beneath the parking lot with a new permeable system."
This attributive use is common and often hyphenated: “stormwater drainage,” “stormwater pipe,” or “stormwater management.”
Usually uncountable in general usage; the plural is chiefly used in technical contexts to refer to distinct flows or bodies of runoff.
"The separated stormwaters carried sediment from the construction site into the stream."
What falls during a storm can become a major urban hazard: every hour of heavy rain sends runoff racing toward drains, streets, and waterways.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does stormwater come from?
“Stormwater” is an English compound formed from “storm” and “water.” The expression originally referred broadly to water falling during a storm, but drainage and engineering usage later emphasized the runoff collected from rainfall and melting snow. Its development parallels the growing use of engineered drainage systems in towns and cities.
How stormwater is actually used
Usually treated as an uncountable noun in general use. As an attributive modifier, it is commonly hyphenated, as in "stormwater drainage," when the compound is being used as an adjective. In engineering and environmental contexts, the term often implies runoff that has flowed across or entered a drainage network rather than all precipitation.