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The Problem of Polluted or Contaminated Water

Though 92% of Americans have water that meets federal safety standards (Freeman & Gower, 2011), this doesn’t necessarily capture the full extent of the problem. Not only does this statistic still leave tens of millions of Americans without a safe source of drinking water, but it doesn’t even begin to address the minute amounts of thousands of chemicals that aren’t regulated which can be found in tap water.

What’s in our drinking water?

Of the 85,000+ chemicals in the Federal Registry, only 91 of these potential contaminates are regulated under the Safe Drinking Water Act. The EPA knows of another 10,000 or so known contaminants that have already been found in tap water, yet only 104 of these are under review for possible EPA regulation. (Barber, 2014)

These water contaminants come from all types of sources: Some get into the water supply from street and agricultural runoff, others as a result of industrial waste, a few are naturally occurring, and yet others are recycled back into the system from human waste. One review found 95 contaminants from treated raw sewage had made their way back into tap water. These included things like antidepressants, antibiotics, the mosquito repellent DEET, cigarette byproducts, and a host of other drugs. While individually they exist in only tiny amounts, the concern is how they might affect people collectively. (Thacker, 2005)

Research from the U.S. Geological Survey in 2010 found that 20% of untreated water samples from nearly 1,000 public wells across the U.S. had at least one contaminant in them, including herbicides, insecticides and gasoline chemicals. Naturally occurring contaminants such as arsenic and radon made up almost 75% of the “higher than human-health benchmarks” contaminants. (U.S. Geological Survey Press Release, May 21, 2010)

Common contaminants in tap water

Here is a look at some of the more common and/or concerning contaminants that are frequently found in tap water:

Trihalomethanes (THMs)
These compounds are released as a result of the water purification process. They are a byproduct of the way chemical disinfectants react with any organic matter present in the water. There are more than 600 of these potentially cancer-causing compounds that have been identified so far, only 11 of which are regulated under state or federal water safety standards.

Pharmaceuticals in tap water
All that medication that people pour into their bodies gets flushed out the other end and ends up in our waterways, where it is then scooped back up and recycled into the water that comes to your tap. These compounds are typically too small to be filtered out using standard treatment practices, so there’s little that can be done about them. A 2008 study found water supplies in 24 major cities across the U.S. all contain trace amounts of pharmaceuticals. (Barber, 2014)

Pesticides in tap water
Runoff from agricultural fields flushes a lot of the pesticides and herbicides that are sprayed on fields into our water supply. While some of this pollution degrades naturally, most pesticides still have a long enough half-life that they can easily maintain their potency once swept up into the water supply. Many people’s homes still test positive for harmful pesticides like DDT, dieldrin and chlordane, which were banned in the 1970s and 1980s. (Heyworth, 2011; These bans were often due in part to half-lives that could stretch decades or even centuries.)

Hexavalent chromium
Hexavalent chromium, listed as a likely carcinogen by the EPA, has been found in the water supplies in 31 out of 35 cities. (Koch, 12-21-2010) In case you were wondering, this is the chemical made famous by the Erin Brockovich movie, though concentrations were much higher in the case the movie was built around. It’s a toxin that in animals has been linked to various cancers as well as liver and kidney damage. It’s often discharged from steel and pulp mills, though it can exist naturally in the environment in small amounts.

The chlorine added to water can have its own toxic byproducts, and it indirectly contributes to many other problems. Chlorine is now largely replaced by a chemical named chloramine, which is essentially a mix of chlorine and ammonia. Though chloramine has lower amounts of carcinogenic breakdown products, it also makes the water corrosive enough to erode the metal pipes, which can mean more lead and other heavy metals in the water supply. (Paynter, 2016) Most water companies add yet another chemical to the water to offset the corrosion caused by chloride.

Chromium 6
In December of 2010 the nonprofit Environmental Working Group found chromium-6, a cancer causing chemical, in more than 30 public water systems. (Koch & Weise, 2011) Chromium 6 occurs naturally in the environment, but high quantities are produced by industrial projects. Pollution occurs when industrial sites fail to follow proper waste disposal methods.

Biofilm is a thin layer of bacterial microorganisms that can adhere to the surface of structures, which may be organic or inorganic. This residue that can build up in older pipes, and can harbor contaminants like e-coli


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