Does the Spearmint lose its flavor on the bedpost overnight?
If you chew it in the morning will it be too hard to bite?
Can't you see I'm going crazy? Won't somebody put me right?
Does the Spearmint lose its flavor on the bedpost overnight?
-- Lyrics by Billy Rose and Marty Bloom, 1924
Imay not know the answer to that one, but I do know the answer to this:
Does the water lose its chlorine when it's standing overnight?
If you use it to make coffee will it smell and taste all right?
If you put it in your fishbowl will the fish remain upright?
Or will they just roll over from the chlorine . . . or from fright?
-- Doggerel by Robert L. Wolke, 2003
In my Jan. 8 column I opined that chlorinated tap water left to sit out overnight will not discharge its chlorine taste and smell, so coffee made with it in the morning will not be chlorine-free. Readers asked, "Then why do tenders of house plants and tropical fish let chlorinated tap water stand overnight before adding it to their plants or tanks?"
First, the house plants. Some people say that watering them with chlorinated tap water is bad, some people say it isn't, and some people say it depends. I hope that settles that.
For fish in an aquarium and for making coffee, however, water containing chlorine can be a problem, not quite as serious for the coffee drinkers perhaps as for the fish, which might die. Hence the habit of aquarium owners and many home or office coffee brewers to let the tap water stand overnight to "let the chlorine dissipate." But unfortunately, that's a hit-or-miss proposition.
The Chemistry
Most of the municipal water purification utilities that disinfect our drinking water with chlorine add the chlorine directly in the form of a gas. Others use calcium hypochlorite or sodium hypochlorite, the same chemical as in household bleach. When dissolved in water, all three of these substances produce hypochlorous acid (chemical shorthand: HOCl), which is the effective antimicrobial agent. The chlorine itself doesn't do much bacteria killing, but it is responsible for the odor because it doesn't react completely with the water, and some of it remains in the form of dissolved gas.
When chlorinated tap water is allowed to stand around, some of the chlorine gas will indeed escape from the water's surface, whereupon both the chlorine odor and the amount of HOCl in the water will diminish. That's because as some of the chlorine departs, the HOCl in the water produces more of it. In Techspeak, the chlorine-plus-water equilibrium shifts to the left. (This will not be on the exam.)
Chemistry class dismissed.
The problem is that the effectiveness of "letting the chlorine dissipate" depends on many variables, including the water's temperature, its acidity or pH, your olfactory sensitivity, the size and shape of the container, the amount of exposed water surface and, of course, its chlorine content, which can vary substantially from one municipality to another and even within each municipality, depending on the system's demand level and how far down the pipeline you live.
Thus, no generally applicable period of standing time, such as the ubiquitous "overnight" dictum, can be depended upon for ridding chlorinated tap water of its taste and odor. I have seen advice ranging from an hour to several days, but if I had to choose one, I'd go with 48 hours, as recommended by what I consider to be the most reliable sources. It still may or may not work for your particular circ*mstances, but it's worth a try.
A sidelight: The longer the water stands, the less HOCl antibacterial power it will have and the more susceptible it will be to contamination. So, refrigerate it? Fine, but refrigeration will effectively put the brakes on the elimination of chlorine, since cold liquids hold more tightly onto their dissolved gases.
The Kicker
An increasing number of municipal water utilities across the nation have been switching from chlorine to chloramine, a reaction product of chlorine and ammonia that has been used here and there for disinfection since the 1930s. Currently, chloramine is being used in more than a third of all water purification plants in the United States. While chloramine isn't as intensely smelly as chlorine, it does have an unpleasant odor. In fact, chloramine is responsible for most of the odor of overpopulated swimming pools and less-than-immaculate spas.
Now here's the kicker: Chloramine does not dissipate from water upon standing, even for a week or more. And according to a study by Gary Burlingame and Alexis Tanjutco of the Philadelphia Water Department, even boiling the water for five minutes removes only about half of the chloramine. Nevertheless, it must be removed from any water that is to be used either in an aquarium or in the dialysis of kidney patients; it's even worse for fish than chlorine is. There are chemical products sold specifically for removing chloramine.
The Washington Aqueduct, which produces drinking water for the District of Columbia, Arlington County and Falls Church, employs chloramine disinfection. If you live elsewhere, call your local water utility and ask if they use chloramine. If so, and your water has an unpleasant taste or smell from residual chloramine, there is little you can do other than putting it through a household water filter that contains activated charcoal. That will remove tastes and smells no matter what their origin, whether chlorine, chloramine or things you'd rather not know about.
I realize that all this sounds rather complicated, but I believe it needs to be aired to counter the widely quoted, simplistic panacea, "Let the water stand overnight and its taste and smell will dissipate." It's important to note, however, that if disinfection is carefully controlled at the water plant, there should be little if any taste or smell in either chlorine- or chloramine-treated water.
Steel Wool Revisited
Perspicacious readers Charles Mann and Mike Briskin tell me of another reason that steel wool may mar the appearance of stainless-steel cookware: Tiny particles of steel from the wool can become embedded in the stainless surface and rust.
Labelingo: The label on Annie Chun's Ginger Chicken Soup Broth informs us that its main ingredient, chicken broth, is made from water and dehydrated chicken broth.
(Have you noticed any silly things on food labels? Send your Labelingo contributions, along with your name and town, to Food 101, Food Section, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or to the e-mail address that follows.)
Robert L. Wolke (www.professorscience.com) is professor emeritus of chemistry at the University of Pittsburgh and the author, most recently, of "What Einstein Told His Cook: Kitchen Science Explained" (W.W. Norton, $25.95). He can be reached at wolke@pitt.edu.
