I’ve been brewing coffee in percolators and drip coffee makers for nearly sixty years. Ever since I was a wee tyke of eleven, I have always started by filling the percolator or the water tank of the coffee maker with COLD water, first as instructed by my mother, and later as instructed by the directions on the can of Folger’s or the user manual of the Mr. Coffee. I never questioned it, or even wondered why. I just internalized the rule: start with COLD water.
Until this week. The water never hits the ground coffee until it’s hot, hot enough to perform the gravity-defying feat of rising up through the tube (or percolator stem) to enter the basket. What difference does it make what temperature it is when it’s first put into the appliance?
How do the people at Folger’s or Proctor-Silex know whether my hot tap water is safe to drink?
And why don’t the Kraft macaroni and cheese people give a similar warning/recommendation? For that matter, why didn’t my parents ever warn us not to drink hot tap water? I’m pretty sure they liked us.
Not just safe, but taste. Try running your hot water until it is as hot as it gets. Fill a glass and allow it to chill in the refrigerator. Taste test it against water from your cold tap.
No-one here has mentioned Legionnaire’s Disease. This primarily occurred in hotels that failed to run their boiler hot enough to kill all the bugs that liked a “warm” environment; breathing the steam in the shower would infect you. Think about that while you’re smelling the coffee.
And my parents and grandmother were adamant about not drinking from the hot tap, so maybe they liked their kid even more.
And I just don’t get “heating the water twice”. I think the instructions that came with my Cuisinart specified cold water, which I always took to mean that pouring boiling water into the reservoir could damage the machine.
Hot but not boiled water loses a lot of dissolved air. Which makes the water taste “off” or flat or stale compared to normal. The longer it sits hot, the more it loses.
Drip or perk coffeemakers heat but not boil most of the water. But it’s only that hot briefly. Some dissolved air is lost but again the end result is the taste you’re used to. If you start with cold.
Maybe the plastic used might leach something in hot water.
However a suggested way to improve the taste of brewed coffee in a drip machine was to let it run a bit with the lid open (in some models that will preheat the water a bit by recirculating it), then close the top. This is to have hot water first hit the grounds and also raise the initial temperature of the water which in most drip machines is too low. Also suggested without the carafe in place at first to quickly fill the grounds basket with water (again only some models can do this) so the coffee can bloom, before replacing it to drain. That last part required timing so it doesn’t overflow.
All of this…it always seemed to me like this was a hold over from decades ago and wasn’t really relevant anymore…but you’re all saying this is ongoing concern?
I suspect they’re not interested in the difference between using cold tap water and hot tap water, they’re interested in the difference between cold water and boiling water.
Do not try to fill your percolator or drip coffee maker (or moka pot) with boiling hot water, you can damage the machine or risk harming yourself in the process. People are dumb, and can very easily think to “speed things up” by boiling the water in a kettle while they get the coffee grounds out of the cabinet, saying COLD WATER makes it very clear what to do.
Is it possible that percolators don’t work as well with hot water? They work slowly by boiling tiny amounts of water at the bottom of a tube that spurts out at the top onto coffee grounds where it then drips through. I think they shut off when all the water reaches a certain temperature. If you start with hot water the process may not go on long enough to get good coffee.
Funny how I was never taught or told that. And the fact is, growing up, I kinda liked the taste of hot water fresh out of the tap. Come to think of it, I do remember it having a sweet taste to it (possibly a red flag for lead contamination). I didn’t have it very often, so I doubt that future archeologists will be unearthing my bones in five thousand years and wondering what an ancient Roman was doing in the PNW.
One of our commercial coffee brewers had a warning on it to use cold water. IIRC, it was something about hot water actually shortening the brew time and making weaker coffee.
And, come to think of it, it may have been a big percolator (which is what the OP asked about).
