In the early 20th century, getting drinking water required using a windmill to extract groundwater into a holding tank, from which the water flowed by gravity to a cast iron hand pump for use. Across the American West in the 1900s, windmills pumped water for farm animals, household use, and irrigation, and at their peak in 1930 an estimated 600,000 wind pumps were in use. The technology has changed little, and similar windmills remain in use today. A windmill uses the renewable power of the wind to lift underground water to the surface, with two valves working in opposition while the windmill motor transmits power through the sucker rod to the plunger, drawing water upward from the strainer at the bottom.