Does The Coffeemaker Purify My Water?

in Brewing Coffee

The short answer is no!

JP and I were tweeting back and forth on Twitter about the importance of your source of water when making coffee.  I wrote recently on the different options between top, filtered, and spring and what it means to the flavor of your coffee.  After all, coffee is 99% water so you should use the best water you can.

There is some misconception that your source of water isn’t important because it’s going to be heated through the course of the coffee being brewed.  If you use a standard drip-brewer, the water will never get hot enough to be considered purified, so don’t consider the heat of the process to be “cleansing” the water that ends up in your coffee mug.  In fact, consider the quality of that water to be the same at the end of the cycle as what you pour into it (for the most part).


For water to be purified by heat, it has to be boiling heat.  The boiling point of water is 212 deg F or 100 deg C (yes, doesn’t Celsius make so much more sense to use?!).  We don’t want to boil water just before its contact with the coffee because “boiled coffee is spoiled coffee” – coffee taste is seriously affected and bitter if it is boiled at any stage.

So, the optimal temperature at which to boil water is 195-205 deg F, hot enough to extract optimal solids, oils, and flavor from the coffee but not hot enough to boil and ruin the coffee.  Heat is needed to extract flavor as the water passes through the coffee in the filter, but it is just shy of enough heat to have a purifying effect on the water, so the water quality doesn’t change to a significant degree.

That means you can’t count on your coffeemaker to purify water as it makes your coffee.  I suggest again to check out the recent post on water quality so you can be sure you’re using the right kind of that all-important ingredient to coffee – the water itself.

7 Comments

  1. I have used a coffee maker for many things besides coffee and sterilized drinking water is one of them. While the article is correct that a coffee pot’s thermostat is set for 195-205, leaving the lid opened on the coffee pot recycles the water until it reaches boiling. Additionally, the process of pasteurization is heating a substance to 140 degrees and keeping it there for a length of time. Percolating water and leaving it on the burner for a while will most definitely pasteurize it, making it biologically safe to drink, at minimum, within 2hrs. Spend some time in a war zone with limited resources and you come up with a lot of neat tricks. It’s nice to have a hot shave with percolated water… 🙂

    Comment by David — December 12, 2014 @ 12:21 am

  2. I use a PUR water filter pitcher. I have run rusty brown nasty water through it and it comes out clean sparkling and free of any odor. A must have to make good coffee. No, I’m not advertising a product. Just stating what works for me.

    Comment by Steve — March 21, 2016 @ 8:38 am

  3. Good to know, Steve. I haven’t had any problems with my Brita, but was thinking the other day about trying something new. I may give the PUR a shot. That’s a great testimonial.

    Comment by Marc Wortman — March 25, 2016 @ 12:30 am

  4. David, great insight, have also put the coffee pot water to use in RV to save on small water heater power or propane use, if there is electricity or generated power. PUR is a great water filter but of late have been researching all foods for healthy aging, water is important. Am going to get a small coffee pot just for heating and further sterilizing just for drinking. With the tips of lid off and time on hot plate, makes sense to me, am limiting microwave use and don’t have a mountain of money to buy a distiller. Thanks!

    Comment by Ruth — May 9, 2016 @ 10:53 am

  5. Hi Ruth, filtered water and heat should be all that you need for a flavorful coffee without requiring use of a distiller or microwave.

    Comment by Marc Wortman — May 10, 2016 @ 12:48 am

  6. Steve,
    While a PUR filter will do exactly as you say, it needs a prefilter in order to maximize the life of the expensive cartridge.
    The PUR (or Brita, or Zero) filter is excellent at removing solids down to the micron size, but they all have limited filtrate (contaminant) storage capacity which really dirty water would exceed in short order.
    I would recommend “pre-filtering” by straining the water through a series of pieces sheets of cloth having ever-tighter weave, and finally through a paper towel or even a coffee filter. It’s slow but will keep the cartridge of your domestic water filter alive longer.
    Using the coffee maker as a water purifier has its own issues, primarily with the residue of mud and other particulates remaining from the “distilling” of polluted water.
    For long-term survival, a properly-constructed sand-filled prefilter would be preferred. After all, commercial sand filters and chlorine tablets have kept many neighborhood swimming pools clean for a century or more.

    Comment by Norris Bettis — June 8, 2016 @ 12:15 pm

  7. Steve,
    While a PUR filter will do exactly as you say, it needs a prefilter in order to maximize the life of the expensive cartridge.
    The PUR (or Brita, or Zero) filter is excellent at removing solids down to the micron size, but they all have limited filtrate (contaminant) storage capacity which really dirty water would exceed in short order.
    I would recommend “pre-filtering” by straining the water through a series of cloths with ever-tighter weave, and finally through a paper towel or even a coffee filter. It’s slow but keeps the cartridge of your domestic water filter alive longer.
    Using the coffee maker as a water purifier has its own issues, primarily with the residue of mud and other particulates remaining from the “distilling” of polluted water.
    For long-term survival, a properly-constructed sand-filled prefilter would be preferred. After all, commercial sand filters and chlorine tablets have kept many neighborhood swimming pools clean for a century or more.

    Comment by Norris Bettis — June 8, 2016 @ 12:20 pm

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