Why use cold water to make coffee?

in Brewing Coffee, Coffee Gear

Question: Marc, Golden Rule # 3 in part is to have water in the fridge in the Brita but does the water HAVE to be chilled? Will the water temp make that much of a difference in a cup of coffee? - Robin

Answer: Robin, that is a great question for a couple reasons.  First, because it comes up all the time.  And second, because I can think of at least three reasons I’ve heard in my life of why you’re supposed to use cold water when making standard drip-brewed coffee.  The reason for cold water that I hear most often is because there is a “perfect” amount of water-extraction of flavor from coffee.

If you don’t extract enough from the coffee, it’s too weak.  But if you like strong coffee, be warned there’s something called overextraction where TOO MUCH solid is extracted from the coffee, making it sludge and not too enjoyable.  It comes down to the brewing cycle and the water’s exposure to the coffee while at the perfect temperature.  The only way to time an electronic drip brewer’s process to do it right is to “set a standard” on the starting temperature of the water.  The machine will run the same heating process no matter what temperature of water so everybody should get a consistent cup as long as everybody starts out with the same starting temperature…cold.  Otherwise, coffees made with water at different starting temperatures would all taste a little differently.  The machine assumes you’re using cold water.

Another reason that I’ve not heard cited as much but that makes sense to me is that the reference to water temperature is under the assumption that most people are using tap water.  And cold tap water is fresher than hot tap water because it hasn’t been sitting in a water heater waiting to be dispensed from the tap.  Better water makes better coffee so this is also very believable.  If this were true and you were using filtered water, it wouldn’t matter what temperature you use.

And finally, I’ve heard that hot tap water has a higher concentration of minerals (unrelated to the water heater) than does cold tap water which absorbs less from the plumbing itself than the hot.  Is that true?  I’m not sure but if it was, it seems the least plausible for affecting the quality of coffee in your cup.

And I hope in not directly answering your question that I have answered your question, Robin!  I personally use cold water, whether tap or filtered because the machine was designed under that assumption.  But I use a filtered water as often as possible.  If that filtered water was not completely chilled, I would use it anyway.


  1. this has been irking me forever and now that my daughter asked me why I harp on using cold water I HAD TO GIVE HER AN ANSWER BECAUSE LIKE MOST MOM’S I KNOW EVERYTHING…..YOU PROVED THAT POINT.


    Comment by theresa — November 27, 2013 @ 11:01 am

  2. Hilarious, Theresa. I’m just happy I could keep your error-free record alive!

    Comment by Marc Wortman — December 4, 2013 @ 12:27 am

  3. My coffee maker does not make the coffee hot enough. So I tried hot water. It tasted fine and was finally hot enough. As per the minerals impurities aren’t they boiled out? Thanks Mark

    Comment by Marie — July 4, 2014 @ 8:52 am

  4. I have a built in Insinkerator instant hot dispenser that dispenses hot 180 degree filtered water, and tried it to make coffee with it. I noticed the brewing time was cut in half, so I suspect that there is a thermostat in the coffee maker that starts the brewing process once the water is at temperature (ideally 205 degrees). If this is true, your comment about the coffer maker starting cold and goes to the same heating temperature every time, would not be correct.

    Also, in colder areas of the world, the water temperature out of the tap can be significantly colder compared to the water temperature in warmer areas such as Hawaii or California. Therefore, if the water was colder to start, it may never reach the ideal brewing temperature without a brewing thermostat.

    I have tried to find information out if coffee makers have thermostats, but have not found if it is true or not. The coffee maker I am using is a Cuisinart DCC-2650.

    So, do you know if there is a brewing thermostat in modern quality coffee makers?
    Would you also please comment on what temperature the cold water should start at and how the water can come to the correct brewing temperature without a brewing thermostat?

    Comment by David — November 9, 2014 @ 1:06 pm

  5. I accidentally made coffee with no coffee in the basket. When I realized what I had done I just poured the hot water back through into reservoir and after doing this time it was the first time I acutually smelled the coffee brewing. And no one noticed a difference in the flavor but did comment on how good it smelled.

    Comment by Carole Allen — November 17, 2014 @ 4:00 pm

  6. This is an interesting topic for me. I use a drip brewing system that fills into a thermal carafe. I noticed that the ending carafe of coffee wasn’t has hot as I liked it so I started pre-warming the thermal carafe with hot water and also using hot water to brew. These changes made a difference both in the temperature of the first cup of coffee poured as well as the longevity of the carafe keeping the coffee hot over time.

    That being said, someone mentioned to me that brewing drip coffee should start with cold water. However, the person that gave me this information didn’t know why the water should be cold. I searched online to see if I could find information to understand if there was a reason to use cold water to brew and came across this post. After reading Marc’s answer/response and the associated comments, it does seem important to know if drip coffee makers have a thermostat or if “The machine will run the same heating process no matter what temperature of water…”.

    Alternately, it would be a good test to brew a pot of water (sans coffee) with cold water, then with hot water and check the temperature of the resulting water in the pot after each cycle. This process could also be used to check the speed of cycle (assuming you use the same amount of water for each pot). This would lend some factual data to make assumptions against regarding the ‘thermostat’ question.

    Comment by Robert — January 1, 2015 @ 11:09 am

  7. Robert, great advice on using a thermal carafe. I have one that I seldom use, but should use more for that second cup out of the chemex that is usually lukewarm.

    As far as a test, I think we’d find the coffees taste different. Since this article was written, I’ve thought more and more about how there likely isn’t a thermostat in most drip brewers. The heating is likely on a timer, and assumes you’re using cold water. It was difficult to get good information that explained this.

    Comment by Marc Wortman — January 9, 2015 @ 2:08 am

  8. I have never bought the cold water rule, especially after I was told that a hot pot (college dorm version of an electric kettle) had to start with cold water. I think this “rule” comes from the percolator. For those younger than Mr. Coffee, a percolator was a nasty way to make coffee. The grind is in a basket over the water. There is a hollow stem that has a pocket at the bottom. Water in this pocket is heated to a boil, so it “blurps” up through the stem to land on the ground coffee, flushing over the coffee repeatedly. The heater stops when all the water in the reservoir has reached the temperature. So, yes, you need to start a percolator with colder water to brew longer.

    But an automatic drip heas water regardless of the starting temperature. (Same for an electric kettle) Which takes longer – counting from 50 to 212 or from 100 to 212? Why not start with water already warmed?

    I’ll never convince my DH that the temperature doesn’t matter when the water is going to sit all night to be started by timer.

    As for drawing the freshest water, are the pipes in your house worse than the ones in the street, where the water has been sitting even longer? The only thing that makes water from outside taste fresher is that the ouside water was at ground temperature, not house temperature. Maybe if you have a well, and lead pipes….

    Apply some scientific method and use Carole and Robert’s tests. An accurate test would be side-by-side machines and blind tastings.

    Comment by Maureen O'C — February 1, 2015 @ 1:32 pm

  9. Hi Maureen, I’m all too familiar with the percolator and still remember it being the brewer of choice in my house until my parents bought their first drip brewer. The “cold water rule” still eludes me since it seems to be standard advice for a drip brewer, but without an explanation why. If I ever meet a drip brewer engineer, I’ll be sure to ask – I bought there’s an interesting and logical explanation why it is so common.

    Comment by Marc Wortman — March 10, 2015 @ 6:36 pm

  10. Standard drip coffee makers don’t have any moving parts. Cold water helps them work more efficiently (faster).

    Take a look at this short video: https://www.youtube.com/watch?v=4j4Q_YBRJEI&list=PLA33BC8305BA0F871&index=12

    Comment by Jeff — April 23, 2015 @ 12:36 pm

  11. Very interesting, and something I didn’t know.

    Comment by Marc Wortman — April 24, 2015 @ 5:25 pm

  12. here’s what i think is the REAL ANSWER. people make coffee all over the place geographically. you have hard water and you have soft water. people who have hard water might have a water softener installed and it is usually not “whole house” but typically confined to the hot water line which is what is used to do all the washing, showering, and cleaning (granted, sometimes mixed with the cold).
    But there are things that can happen to a water softener that can occasionally ‘contaminate’ the hot water line. namely, if the softener is malfunctioning, for example, it may allow ‘salty water’ into the hot water line, which would clearly effect the coffee (but not showering, washing, etc.) i think that’s the main reason. periodically water quality can suffer on the softened line and the coffee would suffer likewise. by using cold water the whole business of “my coffee tastes funny, there’s something wrong with this coffee” is eliminated. and with the amount of water softeners installed across the country that could translate into a lot of complaints about the coffee. using cold water rules that out. such problems would usually go unnoticed when using hot water to cook, wash, etc.. and we never use hot water to drink from the tap, we use cold. so all the problems that water softeners can have are ruled out by simply using cold water. that’s what i think the answer to this baffling question is!

    Comment by Stephen — June 14, 2015 @ 10:20 pm

  13. Stephen, that is a solid answer. I hadn’t considered that use of cold water bypasses any contaminants that may come from a water heater. Very interesting.

    Comment by Marc Wortman — June 29, 2015 @ 6:10 pm

  14. I expect there are two different types of coffee makers to discuss here. Cheap ones (like the one used in the video Jeff linked) won’t have a thermostat. Based upon my experience and others’ comments, I suspect more expensive ones might (I have a $90 Hamilton Beach, so not a boutique piece). I agree with those who say that – excepting some failure or oddity with the water system – there’s no real disadvantage to using hot water when a thermostat is involved, and it should even speed up the process. I haven’t timed the difference, but there is a noticeable increase in brewing speed if I use hot water to start.

    Now, for those coffee makers without a thermostat (all of them, perhaps?). Given the explanation in the video Jeff linked, it’s not a timed process. The brewing, even in that $9 maker, is driven by temperature, so perhaps a thermostat is actually irrelevant. The only issues would be if the water rises too easily (not reaching a high enough temperature first) or gets too hot before it builds enough pressure to rise.

    Comment by Gerry — September 9, 2015 @ 7:40 am

  15. I just bought a 30 cup percolator at auction and without reading first started it up using hot water. we do not use a softener and our well is spring fed. very cold excellent water. I started to worry that it would stop perking because the water was so hot! so far so good though. it seems to be on a timer as our water is very hot. we use alot of hot water and even run out of it. its done im going to try my first cup! brb. color is great, smells awesome and tastes great. just a fyi for people like me who want coffee and iced coffee for the day!

    Comment by cheri — October 6, 2015 @ 10:34 am

  16. thanks for the vote of confidence on my softener theory marc. on the other hand, the house hot water heater problems you mention in your original response are just as valid as well. the hot water could be prone to being held in the tank for longer periods of time than the ”tankless’ cold water and potentially pick up iron and other minerals. and there is the possibility of the hot water picking up more contaminants, etc. by virtue of the temperature and being in contact with pipe materials and minerals. it’s a situation of the possibility of any/all of these problems that could possibly ‘degrade’ the water quality on the house’s hot water system vs the cold water system. i didn’t really notice that you had included those factors in your initial theory. they rank right ‘in there’ with the potential water softener problems that can occur. myself, being in san francisco where the water quality is typically snowmelt and our heater and plumbing is good, i always use the hottest water i can get out of the tap to cut down on brewing time. most all the brewing devices mentioned depend on the boiling water creating the flow of hot water over the ground coffee. if you are confident of your water quality or have a filter, or are just not that much of a caffeine gourmet, just use the house hot water to get to a boil faster. it’s that simple. i think between the two of us we have this nailed. i wonder what the coffee companies would say? it’s probably so ‘grandfathered’ in their brewing archives that no one at the companies even know anymore!

    Comment by Stephen — November 13, 2015 @ 4:45 am

  17. It seems pretty simple to me. The colder the water is when you start, the longer it takes for the machine to heat it up to brewing temperature, so the time the water is in the basket with the grounds is longer giving a stronger coffee. If I use room temperaure filtered well water in my maker it brews fast and the coffee is weak. If I put the filtered well water in a pitcher and keep it in the fridge and use it, my coffee is stronger and tastes much richer. It takes the machine about 50% longer to brew but it is well worth it.
    If I use room temperature water and swing the basket open about halfway through the brewing process the basket is full to the top with water because the machine heated the water too fast and it “flooded the basket”. If I brew with refrigerated water and check the basket halfway through the process, the water is just barely above the grounds. Try it.

    Comment by 4speeder — January 4, 2016 @ 8:53 pm

  18. Excellent comments. I don’t know enough about the mechanics of the conventional drip brewer to know whether the heather is on a timer or on a thermostat. If on a timer, then I understand the impact you point out in your comments. If on a thermostat, would the water temperature not be irrelevant as the water doesn’t make contact with the coffee until the machine starts dripping?

    Comment by Marc Wortman — January 5, 2016 @ 4:36 pm

  19. My maker has neither a thermostat or a timer. It is very basic. As the water passes through a small hole in the bottom of the reservoir the element heats it and it “Burps” it up a tube to the top of the maker where it drips out over the grounds in the basket. So if the water in the reservoir is cold it takes longer for the element to heat it and send it up the tube. If the water in the reservoir is warmer it heats it faster and burps it up the tube at a higher rate.
    No rocket science here. Its very much the same way an old percolator worked back in the day.

    Comment by 4speeder — January 16, 2016 @ 6:43 pm

  20. I was thinking as you described it that it is a percolator. Hopefully it is not letting the water boil right before applying it to the coffee, as water at that high of a temperature will affect the flavor of the coffee. Thanks for the comment!

    Comment by Marc Wortman — January 17, 2016 @ 6:37 pm

  21. I also once forgot to put coffee into our drip machine. I dumped the hot water back into the reservoir and found out that my #2 filter set-up could not keep up with the accelerated flow coming from the heater and check valve. Allow me to say, an unattended coffeemaker that overflows from the top of the filter basket makes a remarkable mess.

    Comment by JB Allen — February 1, 2016 @ 10:54 am

  22. I’ve been there as well, JB. I was once experimenting with putting cinnamon directly in the filter with ground coffee. Too much cinnamon will clog the filter. Imagine the mess you made, but combined with ground coffee that overflowed with the water.

    Comment by Marc Wortman — February 3, 2016 @ 3:37 am

  23. I think it has to do with both limescale and taste.

    Limescale can ruin your coffee pot. Cold water contains less dissolved calcium bicarbonate (almost 2g/100ml less at 20C than 100C). Calcium bicarbonate is in equilibrium with calcium carbonate (limescale), and hence there is a shift for insoluble calcium carbonate to form soluble calcium bicarbonate. It is not that the same limescale formation doesn’t occur using both hot and cold water, it’s just that there is less push to form calcium bicarbonate in hot water, and therefore there is more calcium carbonate formation (i.e. increased limescale).

    As I think has been mentioned, in the old days hot water supply was not drinkable and there was lead in it, etc. Newer water supplies don’t have this problem, but coffee suppliers know that not all coffee drinkers have newer water supplies. Hot water is also un-filtered, and is capable of dissolving far more impurities than cold water.
    There is also the point that some people say oxygen activates flavours in the beans. If this is the case, cold water has far more dissolved oxygen than hot, and would therefore have a better ability to do so.

    Comment by Stephen — March 18, 2016 @ 1:04 pm

  24. Excellent information, Stephen, and important additions to the original article. Thank you for sharing this!

    Comment by Marc Wortman — March 25, 2016 @ 12:31 am

  25. OK, Hello everyone:
    I’m not a rocket scientist but I’m not sure we need to be. What I see here is that all old style percolators and new drip coffee makers are governed by the warming plate. That said, I’m not sure that all drip makers have a thermostat but the old percolators do (coffee does not brew continuously).
    We all agree that both have a tube with water in it and that both have bubbles that push water through that tube.
    The bubbles are caused by the water reaching a temperature of boiling at the warming plate however, the water in the tube cools it as those bubbles rise. The length of the tube is designed for the temperature the manufacturer wants the coffee to be brewed at.
    As far as starting out with warm or cold water…
    Warm water will not cool the boiled, steam bubbles down as far as cold will but we’re only talking about several degrees, between 198 and 202 is optimum according to some experts.
    An old percolator won’t care as only heated water will shower the basket repeatedly whenever the thermostat has the element heat up again, and again, all day long.
    The drip makers, with thermostats, (you can hear them make a noise) when they turn on again only keep the coffee in pot warm.
    Now I use one of those wire screen (permanent) basket filters but drip makers are designed to use paper filters of different shapes which keeps the coffee in contact with the coffee for a designed amount of time. And, although warm water will fill those baskets higher than using cold I do not believe the time frame of that water draining from filter basket would be disastrous to your morning cup of “Joe”.
    Think on this for a moment… The trail cook for all those cattle drives years ago just threw coffee in a pot (with water) and boiled it, poured it in your tin coffee mug (cup) and you drank it grounds and all. Yum!
    BTW, I get very fine grounds in the bottom of my cup using those wire (permanent) filters, it’s not really all that bad though.
    Good luck to you all,
    Don W.

    Comment by Don W. — May 8, 2016 @ 12:59 pm

  26. Good luck and thank you for this insight, Don. With all of the advances made in coffee brewing, it would be quite an experience to try the coffee once served on those cattle drives. Not necessarily a flavorful experience, but an experience nonetheless.

    Comment by Marc Wortman — May 10, 2016 @ 12:51 am

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