Before water enters the turbine or waterwheel of a microhydropower system, it is funneled through a series of components that control its flow and filter out debris. These components include the headrace, forebay, and water conveyance (or channel, pipeline, or penstock).
The headrace is a waterway that runs parallel to the water source. A headrace is sometimes necessary for hydropower systems when insufficient head, or vertical drop, is provided and is usually constructed of cement or masonry. The headrace leads to the forebay, which also is made of concrete or masonry. It functions as a settling pond for large debris that would otherwise flow into the system and damage the turbine.
Water from the forebay is fed through the trashrack, a grill that removes additional debris. The filtered water then enters through the controlled gates of the spillway into the water conveyance, which funnels water directly to the turbine or waterwheel. These channels, pipelines, or penstocks can be constructed from plastic pipe, cement, steel, and even wood. They often are held in place above ground by support piers and anchors.