Tumwater
- County:
- Thurston County
- County Seat:
- No
- Area (mi²):
- 17.744
- State:
- Washington
Tumwater is a city located in Thurston County, Washington. Tumwater has a 2026 population of 27,826. Tumwater is currently growing at a rate of 2.4% annually and its population has increased by 6.44% since the most recent census, which recorded a population of 26,143 in 2020.