I can remember asking myself this question many years ago at my first environmental laboratory job. I was manually shaking out separatory funnels for EPA 625 and 608 and each sample looked drastically different from the next as I was pouring them into each separatory funnel. At the time, I thought the term wastewater meant anything that came from a sewer pipe and that it mainly consisted of human waste. When I looked deeper into the possible sample categories for these methods, I was very surprised by the different sample types required to be tested as wastewater. With that, it prompted me to ask myself well where does it come from?