The 2020 census found 1,809 people in the township.

Located in the north central part of the county, it borders the following townships: The city of Eaton, the county seat of Preble County, is located in central Washington Township.

[5] It is one of forty-three Washington Townships statewide.

[6] The township is governed by a three-member board of trustees, who are elected in November of odd-numbered years to a four-year term beginning on the following January 1.

There is also an elected township fiscal officer,[7] who serves a four-year term beginning on April 1 of the year after the election, which is held in November of the year before the presidential election.