Polder Elsgeest is a former Water Board ( regional government bodies charged with managing water barriers, waterways, water levels, water quality and sewage treatment ) in the Province of Zuid Holland. It lies between the municipalities Sassenheim, Voorhout, Rijnsburg and Oegstgeest. The polder was also known as “Bangdijkpolder” or “Klein Profijtpolder“.

The water board was responsible for the peatery, drainage and water management later in the polder. Since 1999, the polder is drained bij volunteers who operate the “hoop doet leven” windmill, which originally drained the “Kamphuizen” polder.