Vihmavee

Vihmavee is the Estonian term for rainwater, the water that originates from precipitation such as rain or snowmelt. In hydrology, it is distinguished from groundwater and surface water and can be collected for various uses when properly managed.

Harvesting typically involves collecting runoff from roof surfaces via gutters and downspouts, directing it into storage tanks or cisterns. The collected water is commonly used for non-potable purposes such as garden irrigation, landscape watering, toilet flushing, or outdoor washing. With appropriate treatment, it can be used for indoor applications, including drinking, but this requires stringent filtration, disinfection, and monitoring to meet water quality standards.

Quality of vihmavee depends on the catchment surface and atmospheric conditions. It may contain dust, pollen, organic matter, heavy metals from air pollution, and microorganisms. In urban areas, first-flush diverters and filtration systems are used to remove debris and contaminants; storage tanks should be sealed and cleaned regularly to prevent algae growth and pests. In cold climates, freezing can damage storage systems, so insulation or heated tanks may be necessary.

Environmental and economic benefits include reduced stormwater runoff, lower demand on centralized water supplies, and potential savings on water bills. Challenges include ensuring safe water quality, ongoing maintenance, and initial capital costs for equipment and permits where required. Regulations on vihmavee and rainwater harvesting vary by country and region. In many places, non-potable use is allowed with standard safety practices, while potable use requires advanced treatment and compliance with drinking-water standards. See also rainwater harvesting.