Mannheim, OntarioMannheim is an unincorporated community in Ontario, Canada. It is recognized as a designated place by Statistics Canada.DemographicsIn the 2021 Census of Population conducted by Statistics Canada, Mannheim had a population of 1,002 living in 330 of its 332 total private dwellings, a change of from its 2016 population of 982. With a land area of, it had a population density of in 2021.