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Filtered Water: Why it is Essential for the Perfect Cup of Coffee

If you’re a coffee lover, you know the joy that a freshly brewed cup brings. Whether you prefer a hot cup of coffee in the morning, or an artfully prepared cup of cold brew coffee on a hot afternoon, to get the best flavor profile out of your selected coffee you’ll want to use filtered water.

An expert brewer understands the importance of filtered water, but to the everyday coffee drinker the nuances of coffee preparation can be lost. How much of a difference can the water you use to brew your coffee really make? Quite a lot actually. Let’s take a closer look at why.

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Isn’t the Bean More Important?

The coffee bean you use to brew your coffee is very important for the flavor you end up with, but the mistake most people make is focusing only on which type of coffee you purchase. At least equally as important is the water you use to brew your coffee. Here’s why:

  • Water is the solvent that extracts the flavor profile from the coffee beans. What’s in your water affects what gets extracted.
  • Water is the largest ingredient, by weight, in each cup of coffee you drink.
  • Impurities and contaminants in your water will affect the taste.
  • Harmful contaminants in your water not only affect the flavor of your cup of coffee, but your coffee-maker itself.

Is the water more important than the coffee bean you use to brew with? Maybe not, but it’s close. Both the coffee bean and water you use work together to create the perfect cup of coffee. To get the richest, most accurate flavor profile from your favorite coffee bean, you’ll need to use an appropriate coffee water filter.

Viewing Water as a Solvent

If a chemist is interested in making the perfect cup of coffee, they are going to look at the water used in the process not as the vehicle for carrying flavors extracted from the coffee bean, but as the solvent that does the extraction in the first place.

Water is sometimes known as the “universal solvent”, but what exactly does that mean? It simply means that water is capable of dissolving many substances. 

Water is able to dissolve substances it comes into contact with because of its chemical composition and physical attributes. A water molecule consists of a positively charged hydrogen atom and a negatively charged oxygen atom. These charges enable the water molecule to become so strongly attracted to other molecules that it can actually break up, or dissolve, the bonds that hold the other molecule together. 

This is important for coffee brewing because water acts as a solvent as it passes over the ground coffee, breaking apart the bonds that hold certain flavor molecules to the coffee bean and carrying them into the final brew. 

There are two significant factors that can affect which flavor compounds get carried into your final cup of brewed coffee:

  • Water Temperature – The temperature of the water will affect which compounds get dissolved. This is why cold brewed coffee has a different flavor profile than coffee brewed with hot water.
  • Contaminants – The contaminants in your water can affect what flavor compounds end up in your final cup of coffee. This is because certain contaminants, such as hard minerals like calcium and magnesium, actually bond to the water molecule. These minerals can actually increase the number of flavor molecules extracted from the coffee bean, which can significantly alter the flavor profile of your finished cup.

Water temperature and the presence of certain hard minerals can have a big impact on how your water supply acts as a solvent as it passes over your ground coffee beans. However, the contaminants contained in your water can affect the flavor profile in other ways as well. It’s worth spending some time to understand the impact that contaminants in your water have on your favorite beverage. Be mindful that these contaminants will also end up in the food you prepare, which is why cooking with filtered water is such a great idea.

Contaminants are Mostly, but not Always, Bad for Coffee

If you are a coffee aficionado, you’ve almost certainly been told to never brew your coffee using a tap water supply from your faucet. The reason for that is because of the contaminants That may be in your tap water. That advice stems not from the fact that contaminants in tap water can negatively impact your health, though they certainly can, but rather that contaminants commonly found in tap water will alter the flavor of your coffee.


One example of this that is easy to test is the presence of disinfectants. Disinfectants, primarily in the form of chlorine and chloramine, are used by municipal water suppliers to treat water for microbes that can cause waterborne illnesses. Microbes such as viruses, bacteria, and protozoa are the leading cause of waterborne illness in the United States, leading to the infection of around 7.2 million Americans every year. Chlorine and chloramine provide an important safeguard against these illnesses, and are a crucial aspect of water treatment in the United States.

Unfortunately, for disinfectants to be effective they need to persist in the water long enough for it to get to your house, due to the risk from waterborne diseases in biofilms in your water delivery system. That means that when water flows out of your tap, you should expect that disinfectants may be   present. If you aren’t sure, pour a glass of tap water and smell it. You will almost certainly smell the sharp, chemical scent of a disinfectant.

Those disinfectants will alter the taste of your coffee. To remove them, you’ll need to use a filtration system in your home that is capable of removing disinfectants and their by-products. Most commonly this is accomplished through granulated activated carbon (GAC) filtration, which traps disinfectants and their by-products. A kitchen water filtration system is a great option for filtering water for coffee, since it is easily accessible for making your morning cup of coffee.

Hard Minerals

The presence of minerals in your water is a more contentious topic when it comes to coffee brewing. As we’ve mentioned, hard minerals such as calcium and magnesium can actually increase the extraction of flavor compounds from your favorite coffee, resulting in a more robust flavor profile. However, the presence of too many hard minerals can also muddy the flavors of your favorite brew, obscuring and distorting it.

Not everywhere has hard water, so this isn’t a problem for everyone. Water in the Southwestern United States is generally quite hard, meaning that the content of dissolved minerals is relatively high compared to soft water, or water containing little or no hard dissolved minerals. 

Those hard minerals can cause lots of problems around your home. Hard minerals are left behind on surfaces water is heated or evaporated on, such as fixtures around your bathroom or appliances like your water heater, ice machine, and coffee pot. Using hard water to brew coffee will result in mineral buildup in your coffee pot, which will require you to perform more frequent maintenance to keep it operating efficiently. This is also true for the other appliances that we mentioned, such as your ice machine, which is why you should also use an ice machine water filter to help with water hardness.

The lesson for your cup of coffee is that, though you want some mineral content in your water for the perfect cup of coffee, you don’t want too high of mineral content. Not only will it dull or muddy the flavor profile of your coffee, but it will also impact the longevity of your favorite coffee maker. 

What’s the Best Water for a Cup of Coffee?

At Rayne Water we’re experts on water filtration, not coffee brewing. But we know expertise when we see it, which is why we’ll rely on the guidance provided by the Specialty Coffee Association of American (SCAA) for the ideal water to use for brewing your coffee. 

The SCAA breaks down both a “Target” and “Acceptable Range” for water quality, both of which share requirements for odor, color, and chlorine content. According to the SCAA, water you use to brew coffee should be clean and odor free, clear in color, and contain no chlorine. If you’re looking for the best water filter for coffee, you’ll want to use a filtration system that gets you as close to the following thresholds:


For the ideal cup of coffee, according to the SCAA, you’ll want to use water that meets these thresholds:

  • 150 mg/L of total dissolved solids (TDS)
  • 4 grains or 68 mg/L of calcium hardness
  • 40 mg/L total alkalinity
  • PH of 7.0
  • 10 mg/L of sodium.

Acceptable Range

What if you’re not a perfectionist? Good news! The SCAA has guidelines for you as well. They are:

  • TDS ranging from 75 – 250 mg/L
  • 1-5 grains or 17 – 85 mg/L of calcium hardness
  • Total alkalinity as close to 40 mg/L as possible
  • PH between 6.5 – 7.5
  • Sodium as close to 10 mg/L as possible

Closing Thoughts

If you’re passionate about your coffee, you’ll definitely want to use water filtration for coffee you brew. The ideal water used for coffee should be free of disinfectants like chlorine, clear and odorless, have a neutral PH, and some, but not too many, dissolved solids. Striking the right balance is key for drawing out and showcasing the flavor profile of your favorite coffee bean.

While water filtration is important for creating the best cup of coffee, it is also important for protecting the health of yourself and those you live with. Installing an effective water filtration system in your home is the best way to ensure your family is protected against any unexpected rise in contaminants in your tap water. At the same time, home water filtration offers many benefits, including saving you money over time!

If you’re curious about home water filtration systems and want to learn more, reach out to us at Rayne Water today! We’ve spent decades helping households and businesses improve access to clean, filtered drinking water systems, and we’d love to help you find the ideal water treatment solution for your needs. 

Whether you’re simply looking to produce the best cup of coffee possible, or you’re looking for a whole-house filtration system for comprehensive protection, our expert team at Rayne Water has got you covered. To learn more, contact us today!



  1. “SCAA Standard | Water for Brewing Specialty CoffeePublished by the Specialty Coffee Association of America (SCAA)”
  2. “Experimenting with the Effect of Water Quality on Coffee”
  3. “What Is The Best Water For Coffee?”
  4. “You should never brew coffee with tap water. Here’s why”