Downspout

A downspout is the vertical pipe that carries water from the gutter down to the ground and away from the foundation. Undersized or clogged downspouts are a leading cause of gutter overflow.

Downspouts do the real work of moving collected water to a safe discharge point. If there are too few of them, they're too small, or they clog at the elbow or underground, water backs up and the gutter overflows even when the trough itself looks clean. Proper spacing (commonly one per 30–40 feet of gutter), correct sizing, and extensions or splash blocks that carry water several feet from the house all matter. Many "my gutters overflow" problems are actually downspout problems.