Ottumwa is a city in Wapello County, Iowa, United States. The population was 24,998 at the 2000 census. It is the county seat of Wapello County. It is located in the southeastern part of Iowa, and the city is split into northern and southern halves by the Des Moines River. Ottumwa apartments for rent comparison page shows most up to date rent information on Ottumwa apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.