| Breitach | |
| Mouth Coordinates: | 47.4273°N 10.274°W |
| Subdivision Type1: | Countries |
| Subdivision Type2: | States |
| Length Km: | 24.3 |
| Basin Size Km2: | 149 |
The Breitach is a 24adj=midNaNadj=mid mountain river, the southwestern (left) source of the Iller in the Allgäu Alps, in the states of Vorarlberg (Austria) and Bavaria (Germany).
The river originates in, a part of Mittelberg, in the Kleinwalsertal as the union of three smaller source streams. It flows in the northwestern direction through the valley that in earlier times was called German: Breitachtal ("Breitach Valley") after the river. At the German: Walserschanze, the Austrian-German border, the Breitach reaches German territory and curves through the narrow Breitachklamm. Then, the Starzlach flows from the west into the Breitach. At the so-called ("Iller origin") in Oberstdorf, the Breitach, the Stillach and the Trettach flow together forming the Iller.
Of geological interest are the so-called Breitach rocks; a mineral of brown color and of small fracture, it is only found in the Breitach.