Poestenkill is a town in Rensselaer County, New York, United States. USA. The population was 4,054 at the 2000 census. The town is named after Poesten Kill, an important stream in the area. Poestenkill apartments for rent comparison page shows most up to date rent information on Poestenkill apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.