Thursday, August 2, 2007

New York City tap water taste test

Priscilla and I got into a little discussion about the potability of New York City tap water, namely, that I think it's great and she thinks it stinks.

I was convinced that she didn't like the tap water here because she expected it to be bad. Google searches to prove who was more correct turned out to be useless. A blind taste test was in order.

I got tap water from the lab kitchen.

I got Poland Spring from the lab water cooler. I think Poland Spring tastes great. This acted as our positive control.

I wanted to get Aquafina because we'd heard that they just bottle municipal tap water, but it cost $1.75 for a small bottle in all the vending machines around the hospital. I couldn't buy it on principle. What a rip off!

Instead, I got a large bottle of Deer Park, a water that I don't like. This was our negative control.

I marked the cups &alpha, &beta, and &gamma and did not reveal the identities of the waters until after they had been tasted. After pouring the water into the cups, I let them sit long enough to reach room temperature.

There was a threefold rationale to this. First, the bottled waters were colder than the tap, and we wanted to compare everything at equal temperatures. Second, it's easier to taste things at warmer temperatures. The cold can cover up off flavors. And finally, I wanted to let some of the chlorine evaporate from the tap water to give it a better chance.

Priscilla's favorite water was the Poland spring (&beta). Second favorite was the Deer Park (&gamma). And the least favorite was the New York City tap water (&alpha).

She detected an unpleasant aftertaste in the tap water. A nice way to put it is that it had a long finish.

In light of these findings I pleaded the Fifth Amendment and didn't participate in the tasting.

I guess the thing to take away from this is that New York City tap water is really good for tap water. But it can't compare to the good bottled waters out there. Tap water is also handicapped by the chlorine, though I've found that you can eliminate much of the chemical taste of tap water by leaving it in a pitcher overnight.

I can't help but mention a major confounder to the blind taste test. I think it's pretty easy to figure out which water was which because both Poland Spring and New York City tap water have a distinct taste, good or bad. So it is possible that the test was not blind at all, returning to the whole problem of anti-tap bias.


Joshua said...

remember that nyc tap water will taste different in different places depending on the pipes of the building that it passes through. for example the water in the apartment that I grew up in tastes delicious, however the water at Eve's old apartment tastes gross because the pipes were old and grimy...

David said...

Yes, that's right. I didn't take that into account. Also, in some buildings the water is brown whereas in others it is clear. I've been lucky enough to only live in buildings with clear water.

In The Man Who Ate Everything, Jeffrey Steingarten writes about the persistence of chlorine as a function of distance from the nearest treatment station. So that probably also plays a role.