The increased waste produced by growing populations over time eventually led to potential health hazards. It then became necessary to come up with systems to dispose of garbage and human waste in a sanitary manner. Plumbing systems designed to remove waste water from dwellings and public buildings became commonplace, as did sewage plants which treated the wastewater before it was dumped into local waterways. Landfills were established, and garbage was collected for sanitary disposal in dumps and landfills a safe distance from the general population. These measures led to a healthier environment, and allowed for further population growth.