Source : Webster's Revised Unabridged Dictionary (1913)

Standpipe \Stand"pipe`\, n.
   1. (Engin.) A vertical pipe, open at the top, between a
      hydrant and a reservoir, to equalize the flow of water;
      also, a large vertical pipe, near a pumping engine, into
      which water is forced up, so as to give it sufficient head
      to rise to the required level at a distance.

   2. (Steam Boiler) A supply pipe of sufficient elevation to
      enable the water to flow into the boiler, notwithstanding
      the pressure of the steam. --Knight.

Source : WordNet®

standpipe
     n : a vertical pipe