| Schmalwasser | |
| Mouth Coordinates: | 52.7045°N 10.3447°W |
| Progression: | Lutter→ |
| Subdivision Type1: | Country |
| Subdivision Type2: | State |
| Length: | 11.5km (07.1miles) |
Schmalwasser is a river of Lower Saxony, Germany on the southern edge of the Lüneburg Heath.
The Schmalwasser rises near Blickwedel (a district of Sprakensehl), winds southwards, is joined from the left by the Räderbach and discharges into the Lutter in the village of Bargfeld.
The story Die Wasserstraße by Arno Schmidt (1964) is about a walk up the Schmalwasser.