Elsava is a 27-kilometre-long (17 mi) right tributary of the Main in the administrative districts Aschaffenburg and Miltenberg in the Bavarian Spessart.

The short section upstream from Hessenthal [de] to Mespelbrunn is called Kaltenbach.

The original name Elsapha is descended from the Old High German word Els for alder and the Indogermanic word Ap what meant water.

As an explanation "watercourse surrounded by alders" arises from it.

The river Aschaff flowing nearby (from Ascapha meaning "ash water") has also the same name origin.