
Sewage. It's all good, to DEA and health officials. Photo: CC/Les Chatfield
Scientists based in Oregon have been sampling sewerage through the United States, looking for traces of crystal meth, coke and other drugs, including coffee.
This study (excerpt and link, below), boasts new techniques to give authorities a picture of the levels of drug use in areas of concern to the U.S. Drug Enforcement Administration.
Not surprisingly, crystal meth levels are highest in the South and West. (The boffins used a DEA map to guide their sampling.)

Factoid: cocaine is among the most difficult drugs to remove from sewerage during treatment. Photo: DurhamCountyNC.gov
I expect we’ll soon be hearing about a fine-tuned method of capturing what comes out of your toilet when it hits municipal pipes.
That’s when what you flush is no longer yours, and the government can start sniffing.
The observed ranges in index loads for illicit drugs including methamphetamine and cocaine and the regions of the US in which they occur are generally reflective of known drug use patterns in the United States (40, 41). The finding that methamphetamine concentrations for several municipalities are much higher than those reported in previous literature, all of which is from Europe, is reflective of known international drug use patterns (42). Attempts have been made to compare measured values for raw wastewater samples with estimated values (28); however, these have been rudimentary, based upon compounds with complex sociological and pharmacological phenomenon, and have not incorporated components of error surrounding sampling and flow measurements. Additional tools, such as the use of indicator compounds, like creatinine, are needed to enhance our capabilities for comparing the index loads for different municipalities.
via Eliminating Solid Phase Extraction with Large-Volume Injection LC/MS/MS: Analysis of Illicit and Legal Drugs and Human Urine Indicators in US Wastewaters – Environmental Science & Technology (ACS Publications).