How Important is Water in Brewing Coffee?

We always want to drink a well-balanced and delicious cup of coffee. But in case it's not how it goes, it is easy to assume that there is something wrong with the brewing process or the coffee beans. Let's talk about how water is an essential factor that affects the flavor of your coffee. Water is one of the most overlooked fundamentals since most coffee lovers are too concerned with the grind size, freshness, and proportion. We'll also talk about which states in the US have the best water quality. If you're in a state with low-quality water, what are your alternatives or solutions to turning your water into good quality water for brewing coffee?

Water plays a vital role in brewing coffee because it helps enhance and bring out the flavors of the coffee through the minerals present in the water. That said, having the right balance of these minerals will affect the quality of your cup of coffee.

Water used for brewing should be fresh and clean. It also should not contain chlorine, chloramine, and hypochlorite, which is challenging due to the regular disinfecting of water and water pipes. Fresh, cold water is always best to use when heating it to the preferred temperature for brewing coffee. Hot tap water often has an odd and bland taste and smell.

So what's in water that affects the flavor and quality of your coffee? What minerals do we need to extract the flavors of the beans? What kind of water do we need for a great quality coffee?

We discovered that the compounds in "hard water" tend to extract more taste in roasted coffee beans during brewing. Water hardness, in general, describes the number of dissolved minerals in the water. For example, groundwater is harder than surface water because it has been in contact with minerals longer. Water with higher magnesium levels will likely pull more flavors from a coffee bean.

Magnesium and Calcium are helping to pull more taste from coffee beans, so we want just a valuable amount of them. Magnesium has a lot of oxygen, so it has a more powerful extraction than Calcium.

We also want a good amount of Carbonates in our water. Carbonates are in charge of acid buffer capacity, keeping pH stable but not necessarily neutral. Coffee contains weak acids, so it's constantly changing depending on the carbonate hardness due to the buffering capacity of the carbonates. Basically, if we forget about carbonates, our favorite cup of coffee will turn into a bland, tasteless coffee.

  • If water is high in alkalinity, the vibrant acidity in taste (i.e. fruity, citrus, tart, etc..) will be flushed away by the pH buffer. The acidity is still there, but we don't taste it, only left with an earthy, dull, and flat taste.
  • If water is low in alkalinity, the coffee will taste vinegary and sour, so we only add a small amount of pH buffer to it.

The goal here is to get a positive balance between all the minerals in the water. We want our coffee to taste flavorful with a touch of acidity. At the same time, we don't want to descale our coffee equipment frequently.

High-quality water standards

Most waters worldwide are too high both in carbonate hardness and total hardness.

Total hardness (°dH): carbonate hardness + permanent hardness

Carbonate hardness (kH): Bicarbonates + Magnesium + Calcium

Permanent hardness (non-carbonate hardness): Sodium, Potassium, Nitrate and Chloride

SCA (Specialty Coffee Association) standards for minerals:

  • total hardness of 50-175 ppm CaCO3 (2,9-9,8 dH°)
  • carbonate hardness of 40-75 ppm CaCO3 92,2-4,2 dH°)
  • pH level of 6-8 (water is neutral but due to different substances dissolved in water, it can be slightly acidic or alkalic.)

The significance of pH for coffee:

  • Bicarbonate regulates the acidity in your coffee. You want to have at least some alkalinity that keeps the pH level stable (pH buffer) to balance the flavor of the coffee. However, too high in alkalinity will prevent us from tasting the vibrant acidity even though it's present in the coffee. On the other hand, coffee tastes vinegary and sour with too low alkalinity.
  • High water acidity is terrible for extraction but good for flavor.
  • Neutral water is good for extraction but terrible for flavor.
  • The lower the values for total hardness and alkalinity will form the less scale.

For Pour-Over brewing at home, here are some recommended filtrations based on your preference.

Household and Professional Use

  1. Pre-filtration for the particles. This is done to remove any large compounds in water.
  2. Activated carbon filtration. This filtration effectively ties up organic compounds from water such as chlorine, odors, colors, and cloudiness. It does not affect the water's mineral content.
  3. Fin filtration for the particles. This filtration is done after other treatments to remove any excess fine particles from water.

Professional Use Only

  1. Demineralization and mineralization done by ion exchanger or mineral introduction during the filtration. This can be done for either all the water passing through the system or just partially. Some of the removed contents can also be returned to the water.
  2. Reverse osmosis. It is a system where the pressurized water is pushed through a semi-permeable membrane, leaving behind all the other molecules than water. This process is to achieve pure water molecules. Then again, not the best thing to do when brewing coffee.

All these can also be combined into one filtering system.

How to find out what the pH levels and minerals in your water?

You can order water test kits already available online or from your local water testing shops. Or you can contact any water testing shops to conduct water tests at your home. Either way benefit you a great deal for your appliances, water consumption and etc.

Is it worth doing all these?

Yes, it will give you the best quality for brewing your favorite pour over coffee, drinking water, showering, and being safer for your home appliances, including your coffee machines.

Remember, there are no specific values for all the minerals and other contents. What matters is the balance and interaction between the substances.


However, if you want to avoid all the math and hassle of buying and measuring out your own minerals, you can use Lotus Water which contains pre dissolved minerals that are added to distilled water using precision droppers. The solutions are formulated such that adding a single drop of magnesium or calcium to 500 mL of distilled water, the supplied bottle filled to just below the cap, adds 30 ppm as CaCO3 of hardness and adding a drop of bicarbonate adds 15 ppm as CaCO3 of alkalinity. 

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