Wellpoint systems are used to lower groundwater levels to provide stable working conditions. They consist of a series of small diameter wells that are connected by a header pipe to a wellpoint pump. The pump creates a vacuum in the header pipe drawing water up from the ground. Welpoints are typically installed along or around an excavation. The height to which water can be drawn by vacuum in this way is approximately 6 metres. To function at greater depths, well points can be installed in stages as the excavation proceeds.