Catchwater

A catchwater drain decreases the velocity of storm-water runoff to reduce and prevent erosion and other environmental problems.

In Hong Kong there are approximately 120 km of concrete channels, used as gutters built along hillsides in order to direct freshwater runoff into reservoirs for local water consumption.

Rainwater tanks, also known as rain barrels in North America, are used to collect runoff coming from precipitation to prevent contamination from entering waterways.

[4] Rain barrels are large containers that are connected to buildings through a gutter system which catches runoff from roofs.

[7] Due to the expense of these systems, they are generally only to be found where there is an extreme shortage of freshwater, because of geographical or political issues.