Here’s a brain teaser or practical math exercise for you: How much does it cost to boil one quart of water in your microwave? I mean to just bring it to a boil to remove the bad taste of the chlorine gas, which was put there for our health protection.
The factors to consider are the amount of water (1 qt.), how long it takes, the amount of electricity consumed by your microwave and the present price per kilowatt hour of electricity (about 10 cents per kwh). Microwave ovens are sold in many different sizes, and one might do the same job in half the time of another, but their efficiency is so close that it won’t make much difference in cost when the water finally comes to a boil. For example, a 1600 watt microwave will boil the same water in half the time it would take for an 800 watt oven, but they will both use the same amount of electricity in the end.
So, here we go: First, experience with my own microwave tells me a quart measuring cup of water begins to bubble in a boil at 8 minutes and 30 seconds. That is 8.5 minutes. Since one hour is 60 minutes, divide 8.5 minutes by 60. Therefore, the water comes to a boil in 0.1417 hours. (We convert these minutes to hours because electricity is sold by kilowatt hour.)
Secondly, and since my microwave is rated at 13 amps and 120 volts AC, I simply multiply the current in amperes times the voltage. Therefore, this microwave draws 1,560 watts at full current. If it took a whole hour to boil the water (but it doesn’t) that would equal 1.56 kilowatt hours of electricity. (To convert watts to kilowatts, in this example, divide 1,560 watts by 1,000, as “kilo” means 1,000.)
However, it does not take an hour, only 0.1417 hour, to boil the water. So, if you multiply 0.1417 hours times 1.56 kw, you will find the boiling only consumed 0.221 kwh of electricity.
Finally, multiply 0.221 kwh (the amount of electricity used) times the price of electricity at 10 cents per kwh, and the result is that the quart of water cost barely over two cents to boil! How many purifying pitcher filters can you buy for that?
Now let me give you my own “two cents worth.” I don’t think it matters what microwave you use, one rated high or low in watts consumed. The cost to boil any given amount of water will differ very little, though it will be quicker in the hotter models. Boil water on the highest setting. The water will sometimes boil over, and you’ll need to open the oven door to let it dry out. Experiment by watching it a few times until you determine how long it takes in your own microwave, and the duration time will stay almost the same “forever after,” once you complete your experiment and learn the actual amount of time for you.
One caution: Don’t let this boiled water stand around long with all its chlorine boiled out of it, because it had been chlorinated for your health protection before you boiled it. Now I say, “Kippis!” (Finnish for “cheers!”) to enjoying the taste of our Mississippi River water.