Lifting water with the wind
Many people picture a windmill as a place where grain is ground, but a large share of the machines built over the last few centuries did a different job: they moved water. Pumping windmills drained flooded land in northern Europe and filled stock tanks on the American plains. The wind turned a shaft, the shaft worked a pump or a scoop wheel, and water went where people needed it. The mills that ground grain are covered elsewhere on this site; this article follows the ones that pumped.
Older ways of raising water
Raising water by muscle is far older than windmills. Devices such as the shaduf irrigation lever, the bucket-and-rope hoist and animal-driven wheels moved water in the Nile valley and Mesopotamia for thousands of years. Chinese records also describe windmills of a vertical-axis, mat-sail type used to lift water, though the dates of these machines are less certain than the evidence for the mills of Persia and Europe. Windmills added a new source of power to an old task, and in places with steady wind they replaced human and animal labor.
The Netherlands and the drained polder
The Dutch are the classic example. Much of the Netherlands lies close to or below sea level, and from the Middle Ages communities built dikes and pumped out water to create dry farmland, known as polders. Early drainage mills are often traced to around the fifteenth century, and at first they were small post-type mills that lifted water a short height at a time.
Windmills took on more of the work through the sixteenth and seventeenth centuries. A scoop wheel or an Archimedes screw, a large screw turning in an inclined trough, lifted water from a ditch into a higher channel. Where the drop was larger, mills were arranged in a staircase, each lifting the water a stage higher. Large-scale projects, such as the seventeenth-century drainage of big inland lakes in North Holland, relied on these windmill systems, and the many canal locks and sluices of the Dutch landscape formed part of the same system for managing water levels.
The mills at Kinderdijk, built in the eighteenth century, remain the best-known surviving group. Nineteenth-century drainage began to rely on steam engines, one famous example being the Cruquius pumping station, built for the draining of the Haarlemmermeer lake in the 1840s. Steam-powered pumping, and later electric and diesel pumps, gradually took over, and the older mills became heritage sites, though some are still kept operational or used as reserves.
The American windmill
The American story is a different kind. In the middle of the nineteenth century, settlers moved onto the Great Plains, where surface water was often scarce and the wind was steady. A wooden windmill with a slow turning wheel did not suit the job. Inventors, including Daniel Halladay in the 1850s, developed a lighter wheel with many narrow blades that adjusted itself to the wind and turned a rod up and down to work a pump. Later makers refined the design in steel, with a rudder-like tail vane that turned the wheel to face the wind.
These machines were suited to the work. The many blades gave plenty of turning force at low wind speeds, which is what a piston pump needs to lift water from a well. A windmill could fill a tank slowly all day, even with no one watching. That made them useful for farm households and for cattle, and a ranch could have stock water far from any river. The spread of barbed wire in the same period, which allowed ranchers to fence large tracts, made it more important to have reliable water points in each pasture.
Railroads were a major early customer as well. Steam locomotives needed large amounts of water, and trackside windmills filled the tanks at stations along lines across dry country. Farm windmills were everywhere in rural America by the early twentieth century.
Decline and survival
Rural electrification, which brought electric motors to pump water on demand, reduced the need for windmills in the mid-twentieth century. Pumps powered by diesel engines did the same in other regions. Many windmills were left to rust, but they never disappeared completely. Multi-bladed windmills are still used in parts of the American West, Australia, Argentina and southern Africa, where remote livestock water supplies are costly to serve with power lines. Solar pumps now compete with them in the same niche.
Why the pumping windmill matters
Pumping windmills show that wind power was often a tool for survival and settlement, not a luxury. They allowed farming on land that would have flooded, and ranching on land that would have been dry. Their ability to run unattended and store water in a tank, a built-in form of buffer against calm days, is a design idea that engineers still discuss when looking at renewable power. Details such as how many windmills once operated are uncertain, since records were scattered among many small manufacturers, but the scale of their use is clear from the landscapes they left behind.