The KDW – Kampf Doppeldecker, Wasser (Fighter Biplane, Water) – was adapted from the Hansa-Brandenburg D.I landplane to provide coastal defence over the North Sea.

To counteract the keel effect resulting from the floats, which were below the aircraft's centre of gravity, vertical tailfin area was added below and later above the fuselage.

Starting with the second batch a light steel-tube vee brace was added outboard of the star struts to stiffen the outer upper wing.

The final batch of 20 aircraft, delivered between October 1917 and February 1918, were armed with twin Spandau machine guns on either side of the cockpit.

[3] Another reason it was unpopular with pilots was that, until the final batch, the armament was positioned out of their reach, making it impossible to clear stoppages while airborne.