Drinking water. In the walls, beneath the streets, around the world, it races through unseen pipes to fill tens of billions of glasses, cups, and bottles each day and to quench that most essential of human drives, thirst. For millions of years, intimate knowledge about the source of our water was among the most important bits of information our ancestors carried. Today that intimacy is lost.  We turn on a tap and water flows as if by magic. We have come to accept the illusion as reality.  Most of us have little awareness of the source of our drinking water.  We assume it will be there.  We assume it will be safe.

The road to disaster is paved with assumptions.  The largest waterborne outbreak in U.S. history happened not centuries ago, but in 1993.  In 2000, contaminated drinking water sickened hundreds and killed six people in a small Canadian city.  Not only does waterborne disease still happen, but we don’t even know how often it occurs.  Our system for detecting waterborne disease is so limited that drinking water is never even recognized as the cause in the vast majority of cases.  Evidence suggests that drinking water may sicken millions of people every year in the United States. 

For much of the developing world, waterborne disease is no secret. Like a tsunami in slow motion, unsafe drinking water is killing constantly; almost 40,000 people will die this week alone. Unlike a tsunami, it never stops.  

In 1994, cholera swept through a crowded refugee camp in Goma, Zaire and killed 60,000 people in less than a month.  It was the worst outbreak of waterborne disease in human history. The horror of Goma lies so far beyond the realm of experience for most of us that it takes on a sense of the remote and abstract.  The gap between an epidemic in Goma and the sanitary comfort of the developed world seems vast, but for many reasons, this chasm may not be so wide and impassable as we would like to believe.  Just 100 years ago, waterborne typhoid fever was a leading cause of death in the United States.  Less than 50 years before that, the major cities of Europe and North America were ravaged by waterborne cholera.  The only thing that separates us from Goma is the systems we have developed to transport and treat our sewage and drinking water.

The operation of our water supplies is, to most of us, invisible. Invisibility encourages complacency. We have come to think of these systems as failsafe, but the technology we rely on for treating most of our drinking water is almost a century old and many of our water treatment plants have been in operation since the early 20th century.  

At least some of the water from these aging plants is, quite literally, treated sewage.   Farm runoff, industrial waste, and sewage, both treated and untreated, routinely find their way to the intakes of our water treatment plants.  Studies have shown that some of the pathogens (disease causing microbes) from these sources can and do make their way into drinking water supplies, sometimes causing devastating outbreaks and frequently causing sporadic cases of disease. These diseases are not as deadly as cholera, but it is possible that this may not always hold true.  

 
To understand where this story might lead, we must turn to its beginning.  We must go back to a time when the difference between Goma and the developed world was far smaller, a time when we understood far less about health and disease and had no idea that a glass of water could kill.