Have you ever wondered, just how is tap water tested for contamination, anyway? I thought that my readers would probably find that interesting. I often recommend testing for well-owners. I often write about the different contaminants that are present in the waters of our world. But, how do we know?

The testing that is used depends on the type of contaminant. So, I have broken the question down into three categories, relating to specific contaminant types.

When it comes to bacteria, how is tap water tested for contamination?

Microscopic evaluation will reveal the presence of bacteria, but you can only look at a drop of water at a time. That’s not really enough to make a reliable conclusion. Besides, when it comes to testing water supplies, there are more reliable tests.

Specific bacteria react with specific substances in known ways. For example, an enzyme substrate called magenta GLUC is used to test for E-coli. Only a single type of bacteria may be tested for at any one time. So, numerous tests are usually conducted to check for E-coli, cryptosporidium, giardia, Legionella and other bacteria that cause waterborne illnesses.

When it comes to chemicals, how is tap water tested for contamination?

When we think of chemicals, we think of things like chlorine. But, everything, animal, vegetable or mineral has a chemical composition. Through studying these compositions, scientists have learned that chemicals react with one another in specific ways.

Reactants are chemicals compounds that are known to react in certain ways in the presence of other chemical compounds. Reactants are used to test water for contaminants.

For example, if you wanted to detect the presence of nitrogen, sulfur, fluoride, chlorine or bromine, you could use a sodium fusion test. The reactant is sodium, but the process requires heating the sample. A simple litmus paper test will reveal the presence of chlorine and give you a “high, medium or low” result.

How is tap water tested for contamination by the EPA?

The EPA uses nearly a thousand different tests to determine the type and amount of contaminant present in a supply. They use gas chromatography to test for volatile organic compounds or VOCs. They use spectro-photometry to test fro nitrogen and nitrites. There are thousands of different pollutants in the environment and each has its own test.

The thing that I would like for you to realize is that most home-tests are largely inaccurate. The ones that are very accurate are also very expensive. Collecting a sample and sending it to a qualified laboratory is a good choice for a well-owner. This kind of testing is basically unnecessary for a person service by a public treatment facility.

It isn’t that there are no contaminants in your supply; it’s just that we know what they are likely to be. The levels of contaminants change as time goes by. So, you’d have to test several different times to get accurate results.

How is tap water tested for contamination at home? Do it yourself-tests are mostly inaccurate. Buy a high quality tap water filter and stop worrying.