Windmill "Onrust" (Dutch for unrest) was build in 1809.
It is still in full use for drainage, and controls the water level of the "Naardermeer". This nature reserve (680 ha / 1700 acres) with lakes and marshland is located just southeast of Amsterdam.
When this mighty machine works at full throttle (120 ends = 30 rpm) it pumps out 7200 m3/hr. Even so, it takes 12 hours to lower the water level 1 cm in the area. A wind force of 3 Bf (±9 kts) to 7 Bf (±30 kts) is needed to do the job.
National Parks service, owner of this windmill : www.natuurmonumenten.nl.
More windmills on the countryside video page.