A downspout, downpipe, roof drain pipe, or leader is a vertical

Vertical

Vertical may refer to:*Vertical direction, the direction aligned with the direction of the force of gravity, as materialized with a plumb line...

 pipe

Pipe

Pipe may refer to:* Pipe , a hollow cylinder following certain dimension rules* Smoking pipe* Pipe or butt, a cask measurement* Pipe , a type of metal casting defect...

 for carrying rainwater from a rain gutter

Rain gutter

A rain gutter is a narrow channel, or trough, forming the component of a roof system which collects and diverts rainwater shed by the roof....

 to ground level

Storey

A storey or story is any level part of a building that could be used by people...

. There the water is directed away from the building's foundation and to a sewer

Sewerage

Sewerage refers to the infrastructure that conveys sewage. It encompasses receiving drains, manholes, pumping stations, storm overflows, screening chambers, etc. of the sanitary sewer...

, rainwater harvesting

Rainwater harvesting

Rainwater harvesting is the accumulating and storing of rainwater for reuse before it reaches the aquifer. It has been used to provide drinking water, water for livestock, water for irrigation, as well as other typical uses. Rainwater collected from the roofs of houses and local institutions can...

, or let into the ground through seepage.

The bottom of the downspout often has an elbow which directs the water away from the building.This is to protect a building's foundation from water damage. Decorative heads are occasionally added, these being low-height gargoyle

Gargoyle

In architecture, a gargoyle is a carved stone grotesque, usually made of granite, with a spout designed to convey water from a roof and away from the side of a building thereby preventing rainwater from running down masonry walls and eroding the mortar between...

s.