While this can be a very difficult issue to investigate, buyers of rural, mountain and commercial properties in particular should consider how the property may have been used by previous owners. For example, if you find a dump site with old barrels, you could be buying into a hazardous waste site that could quickly bankrupt you. Issues of prior use can impact more urban subdivisions as well. Homeowners in an unincorporated area of north Boulder discovered several years ago that a film processing plant had contaminated the ground water. The EPA threatened to make the area a Superfund site unless the homeowners agreed to annex to the city of Boulder and connect to the public water system. There are only two things I can recommend here. First, ask city or county planners about previous uses of the property. Second, if you have concerns, there are companies that will conduct an environmental risk assessment for you.