| Official Name: | Sefid Ab |
| Native Name: | سفيداب |
| Settlement Type: | village |
| Pushpin Map: | Iran |
| Mapsize: | 150px |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | Qazvin |
| Subdivision Type2: | County |
| Subdivision Name2: | Qazvin |
| Subdivision Type3: | Bakhsh |
| Subdivision Name3: | Alamut-e Gharbi |
| Subdivision Type4: | Rural District |
| Subdivision Name4: | Rudbar-e Mohammad-e Zamani |
| Population As Of: | 2006 |
| Population Total: | 507 |
| Population Density Km2: | auto |
| Timezone: | IRST |
| Utc Offset: | +3:30 |
| Timezone Dst: | IRDT |
| Utc Offset Dst: | +4:30 |
| Coordinates: | 36.5681°N 50.3447°W |
Sefid Ab (Persian: سفيداب, also Romanized as Sefīd Āb and Safīd Āb) is a village in Rudbar-e Mohammad-e Zamani Rural District, Alamut-e Gharbi District, Qazvin County, Qazvin Province, Iran. As of the 2006 census, its population was 507, in 110 families.