Remember those Back to the Future scenes where Doc Brown talks about flux capacitors? Boiling chlorine out of water is far less cinematic but just as satisfyingly predictable. The process relies on something called Henry’s Law: basically, the amount of gas dissolved in a liquid is proportional to its pressure and temperature. Heat the liquid, and the gas says, “Peace out,” and floats away.
This is also why a good simmer works almost as well as a furious boil. You don’t need a violent rolling chaos—just sustained heat. For the ultimate efficiency, leave the pot uncovered. A lid traps the steam—and the chlorine—forcing it to condense back into the water. Cover your pot, and you’re basically recycling that pool smell.
Fun fact: this volatile escape is the same reason why hot showers produce that “chlorine shower head” aroma. The steam from your morning rinse is doing the work, just without the pasta.
Practical Tips for the Everyday Dechlorinator
You don’t need a lab coat or a subscription to a water-testing newsletter. Here are three ways to put this knowledge to use right in your own kitchen. First, boil for one to three minutes uncovered, then let the water cool naturally—you’ll taste the difference immediately, especially if you’re making tea or coffee where chlorine’s metallic notes can ruin the brew.
What Chemical Removes Chlorine From Water at Diane Rearick blog
Second, if boiling feels too energy-intensive, try the countertop shortcut: fill a pitcher and let it sit uncovered for about 24 hours. Room temperature works, and sunlight speeds it up (a trick aquarists use for fish tanks). This method won’t remove chloramine, though—a longer-lasting disinfectant some water systems use—but it handles free chlorine beautifully.
Third, always let the water cool before using it on sensitive plants or your fish tank. Pouring boiling water into a goldfish bowl is a plot twist no one wants. Your finned friends prefer dechlorinated water at room temp—trust us, they can’t text you their complaints, but they’ll definitely float them.
