If authorities wanted to determine how pervasive the problem of illicit drug use was in their communities, how could they do it? One cheap and easy way has just been tried experimentally in Oregon. Based on the principle that what goes in must come out, researchers measured the amounts and kinds of drugs that made their way through users to become included in untreated wastewater. This first-of-its-kind research is reported in the journal Addiction. Ninety-six municipal water treatment facilities across Oregon volunteered for the study, which concentrated on finding evidence of the drugs meth, cocaine and ecstasy. All samples were collected on the same day, in areas that include about two-thirds of that state's population. Some findings: evidence for cocaine use was primarily in urban areas, almost nonexistent in rural regions; ecstasy use tended toward urban areas as well, and only turned up in about half of all communities; meth was everywhere. More important than those one-day snapshot findings, however, is that this methodology was proven viable, and could be used to track patterns of drug use in multiple regions over time.