On August 6, 1996, President Bill Clinton signed the Safe Drinking Water Act Reauthorization with these words:
“A fundamental promise we must make to our people is that the food they eat and the water they drink are safe.”
Unfortunately, nearly ten years later, it is still a ‘fundamental promise’. In our highly industrialized society, there are hundreds of sources of water contamination. Drinking water sources are subject to contamination and require appropriate treatment to remove disease-causing agents.
The Environmental Protection Agency is charged with overseeing and regulating the quality of our drinking water. The EPA has established ‘acceptable’ standards for only 80 of the toxic bacteria, minerals and other contaminants that pollute both surface and ground water.
Water contaminants enter the water supply through multiple sources, both natural and human-produced. Just as ground water generally moves slowly, so do contaminants in ground water. Because of this slow movement, contaminants tend to remain concentrated.
The most typical sources of surface water contamination are:
||Deposits of minerals, decaying organisms in water|
||including pesticides, irrigation methods, soil contaminants, animal waste|
Air pollution is a major source of water contaminants. As water condenses and becomes precipitation, it may pick up particles from the air and dissolve them. These minerals and other impurities become water contaminants either directly when the rain falls into open bodies of water, or indirectly through runoff and groundwater contamination.
|Industrial wastes, incinerated chemicals and wastes, pollutants from emissions from automobiles, etc. including nitrogen, mercury, copper, PCB, chlordane, lead, lindane, diazanon, hexachlorobenzene|
Construction of buildings, roads, bridges that disturb the soil
|Increased sediments in water|
Soils and sands that settle on ocean floors and lake/river bottoms.
|PCBs, chemicals from industrial plants, fertilizers, pesticides that may have been used decades ago|
|Combined Sewer Overflows
Old sewer systems that carry both storm water and sewage, designed to overflow into surface streams and rivers as a ‘safety measure.’ Combined sewer systems serve roughly 950 communities with about 40 million people.
|Untreated human wastes, industrial waste, toxic materials, debris from sewer systems.|
|Industrial Point Sources
Pollution by industrial sources from discharges, runoff, and land treatment of wastes.
|Industrial chemicals, heat which may kill fish and other organisms, contributing to organic pollution|
||Leachate, leached water from waste disposal systems that leaches into groundwater|
|Marinas and Harbors
||Fuel, petroleum products from boat cleaning, fueling, and maintenance, waste water treatment|
|Municipal Point Sources
||Discharges from municipal water treatment plants|
Catch-all term for surface water contamination that happens during runoff, when water runs over city streets, fields, parks, forests etc, on its way to a surface water source
|Fertilizer, pesticide, herbicides, oil, grease, toxic chemicals, sediment, salt, acid, bacteria from livestock and pet wastes, faulty septic systems|
||Sludge and bacteria leakage|
|Urban Runoff/Storm Sewers
||Sediment, solid waste, decaying vegetation, oil, grease, chemicals from cars, fertilizer and pesticides from gardening, bacteria and viruses, road salts, heavy metals, sediments|
Among the contaminants that have raised alarms in recent years are arsenic, lead, copper, mercury, e. coli, and giardia. All of these water contaminants must be removed from water before it is potable
or safe to drink. In addition, some of the treatment methods – chlorination in particular – create their own byproducts which are at best unpleasant, and at worst toxic.
Municipal water supplies are required to test their water for as many as 80 different contaminants that have immediate health consequences, but the levels of contaminants allowed in water is not 100% safe for all people. In addition, there is a list of ‘secondary’ contaminants that are suggested for regulation, but are not regulated because their effects are only cosmetic and don’t affect the safety of the drinking water. Finally, there are several dozen more contaminants which have health effects, but which are still under consideration for regulation. It’s no surprise, then, that even the EPA recommends that those with compromised immune systems, children and the elderly take special precautions with public drinking water sources.Last Updated: May 16th, 2013