Just noticeable: erasing place in municipal water treatment in the U.S. during the interwar period

For centuries noses, eyes, and mouths have assessed the safety of drinking water. Yet by the end of the long nineteenth century, the nascent professional water worker corps in the United States and Europe began to distance themselves from everyday sensory approaches to judging a water's potability. Historians and geographers have explored the rise of urban water infrastructures as well as shifting approaches to water analysis. However, the changing role of sensory analysis in erasing waters’ biogeophysical histories, as well as the political ramifications of creating authoritative modes of sensory labor that exclude aesthetic evaluations of quality, remains relatively unexamined. This paper asks how water workers’ efforts to standardize and make objective the embodied labor of managing municipal water shifted not only how sensory knowledge is made, but also who has access to sensory knowledge about place. Drawing on technical documents, scientific papers, and production manuals, I examine the emergence of a new standardized system for characterizing and mitigating off odors and flavors found in raw and treated water during the first half of the twentieth century in the United States. This analytical assemblage was built on the precepts of nineteenth-century Fechnerian psychophysics. Grounded in the idea that small increases in stimulation are proportionally accompanied by small increases in sensation, psychophysics offered a way to express and test the relationship between stimulus and experience by identifying the point at which a difference in stimuli was ‘just noticeable’. Through attending to the role of tasting, smelling bodies as sites of scientific knowledge production, and as sites where scientific knowledge is called into question, I show that water workers used estimation of the ineffable to break away from or transcend locale. In the process, they made the water treatment laboratory into a space thoroughly embedded in place, even as they in turn set in motion efforts to remove place from the water sent to consumers throughout the provisioning system.