Tap vs. Bottled Water: A Middlesex Taste Test

In 2013, Concord, Massachusetts (home of Middlesex School) became one of the first communities in the nation to ban the sale of single-serve plastic water bottles.   Campaigns against plastic water bottles argue that bottled water uses more than 17 million barrels of oil annually, enough to fuel 1.3 million cars for a year (see www.banthebottle.net).  Proponents of bottled water bans also argue that most plastic water bottles are not recycled and therefore end up in landfills.  Bottled water supporters, on the other hand, cite the positives:  taste, quality, and convenience (see www.bottledwater.org).

The Test

Common Sense, the Middlesex environmental club, teamed up with our Statistics classes to test the assumption that consumers can taste the difference between bottled water and tap water.   Common Sense ran a double-blind test, in which neither the taste testers nor the test administrators knew which water was which.  Students and faculty sampled three types of water: bottled water, filtered water from a Middlesex dormitory filtered water dispenser, and tap water.  All three samples were served at room temperature, and taste testers rank ordered their preferences (1 being the best and 3 being the worst), offering qualitative comments when desired.  

The Results

Students and faculty were able to tell the three types of water apart with statistical significance (p<1%), ranking them from best to worst 1) bottled water, 2) filtered water, and 3) tap water. The biggest contributors to the statistical test were the number of 3s given to tap water, which was cited as having "an aftertaste", along with the number of 1s given to bottled water.  A few testers thought filtered water was actually bottled water.

Common Sense works to raise awareness of environmental issues on campus.  Previous campaigns have included composting, recycling, and waste reduction.

photo by Steven Depolo

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