A Science of Impurity.

Introduction

This book is about the application of science to one area of public decision making, the determination of water quality. It is a universal concern, though one which has until recently seemed unproblematic to most of us in the industrialized west. The quality of our water was one of those things we had forgotten how to worry about; we could rely, we felt, on the authority of our authorities: on the bacteriologists and engineers with their cultures and chlorine, on the managers and lawyers who would ensure that enough good water continued to reach us. Many things now threaten that trust: a new generation of toxic wastes, growing demand for water in arid regions, the prospect of changing climate and, in the United Kingdom, the sale of water supplies to private investors. All these matters have become public issues and no longer do we assume that good and safe water will always come from the tap. Some buy bottled water, an ironic throwback to the days of the water carrier, others equip their taps with the newest in domestic filters, an appliance common in the nineteenth century, others drink anything but water, a practice that spurred nineteenth century temperance reformers to insist that public authorities provide good, pure water for all. 

We are thus at the end of a period of sanguine ignorance, and water has become another of the many aspects of our world in which we fear crisis. To resolve such questions we look to technical solutions, but when we look to those who usually supply such authority we find some who reassure us that all will be well and others who seem bent on deepening our anxiety. Thrust into the midst of technical controversies on matters about which we know little, we are left to worry both about the supposed dangers themselves and about the rationality of our fear.