Floodwaters

Floodwaters are water that covers land beyond the normal river channels or shoreline, typically resulting from heavy rainfall, river overflow, dam or levee breach, or coastal storm surge. They can also form from snowmelt or dam releases. The speed and depth of floodwaters vary widely, from shallow sheets to fast-moving torrents several meters deep. Urban and rural areas alike can be affected, with water moving unpredictably due to terrain and built structures.

Floodwaters pose multiple hazards: drowning is a leading cause of flood fatalities; even shallow or slow-moving water can knock a person off balance, and moving water has enough energy to sweep people away. Debris, open manhole covers, hidden hazards, and downed power lines increase risk. Floodwater may be contaminated with sewage, chemicals, oils, and other hazardous substances, creating health risks for skin contact, inhalation, or ingestion.

Infrastructure and property sustain damage from inundation. Water can erode foundations, contaminate drinking-water supplies, compromise electrical systems, and overwhelm drainage networks. Sediment deposition and erosion can alter landscapes and floodplains for years after an event.

Public safety guidance during floods typically emphasizes avoiding contact with floodwater, not driving through flooded roads, and seeking higher ground or evacuation when advised. After floodwaters recede, cleanup should include disinfection of touched surfaces, testing of drinking water, and professional assessment of structural integrity.