Chlorine In Bottled Water?

Have you ever wondered if chlorine is in bottled water? The internet is a vast universe of information, and it’s hard to know what source to trust when seeking answers to questions like this. I’ve been curious about chemical content in bottled water for over 2 decades but never had the opportunity to test water for myself, until now.

Hypothesis

My hypothesis for this experiment is that many popular brands of bottled water contain chlorine.

Reasons For This Hypothesis

As a water operator, I know that the standard method for disinfection of tap water is chlorination. Under federal law, operators are required to ensure that the farthest distribution point from a water disinfection plant has a minimum chlorine residual of 0.2mg/L free chlorine or greater.

In other words, all tap water in the United States is required to have chlorine in it to prevent bacterial growth.

Bottled water seems like it is just another form of distribution, so it makes sense that it would need the same safety measures in place as tap water.

Furthermore, many online sources claim that bottled water is just tap water from city water plants like the one I work at.

Materials

For this experiment, I used the following materials:

2 Hach Brand SL 1000 Portable Parallel Analyzer
Free Chlorine Chem Keys
Total Chlorine Chem Keys
4 Popular Bottled Water Brands: Aquafina, Dasani, FIJI, and Smart Water

Process

Testing free chlorine and total chlorine is is simple with the SL 1000 Portable Parallel Analyzers, so there is very little room for error. This was my process:

Inserted total chlorine chem key into one SL 1000
Inserted free chlorine chem key into another SL 1000
Filled the SL 1000 reservoir to the fill line with one water brand at a time
Dipped the total chlorine chem key into the reservoir
Dipped the free chlorine chem key into the reservoir
Waited for results
Recorded results
Rinsed out reservoir 3 times with distilled ionized water before starting new water brand test. (This is standard lab practice to ensure that test results are not cross-contaminated.)

Bonus Experiment pH Of Bottled Water

As a bonus experiment, I decided to test the pH of bottled water, too. This process is simpler than chlorine testing. I placed the water in a cup and dipped the pH probe into the water, hit the “read” button on the pH meter, and recorded the results. Like with the SL tests, I rinsed the cup 3 times with distilled ionized water in between water brand tests to ensure accurate results.