Water Chem

Water is obvious but often overlooked ingredient in coffee, and plays a complicated role in determining flavor. Several factors are at play in your water, including chlorine content, total dissolved solids, hardness, alkalinity, pH, and more. All of these factors have ideal or suggested measurements for the best testing results.


  • Odor
    • You want your water to smell clean and fresh.
  • Color
    • Your water should be completely clear.
  • Chlorine
    • Ideally, chlorine content should be zero for brewing espresso. Municipal water tends to have added chlorine to help fight microbes. Chlorine can affect flavor and, due to the high temperatures and pressures in brewing espresso, hydrochloric acid can be created. This will damage your stainless steel wares over time.
  • TDS
    • The Total Dissolved Solids describes the overall mineral content of your water. A high TDS results in a more mineral taste and reduces flavor extraction. A low TDS can result in over extraction and a tannic, dry aftertaste. The range of TDS you want to fall between is from 75-250mg/L. The ideal would be around 150mg/L.
  • Hardness
    • Water hardness describes the calcium carbonate content in your water. This is important when water reaches temperatures over 180 degrees, like it would in an espresso machine. After that threshold, calcium carbonate becomes a solid, leaving behind scale. Water softeners or espresso machine filters can help reduce water hardness.
  • Alkalinity
    • This is a measure of all alkaline substances in your water and describes your water’s resistance to change in pH. The ideal alkalinity here would be 40 mg/L. A high alkalinity can result in calcium carbonate and accelerated scale build up, as well as an uneven extraction.
  • pH
    • The goal is for the pH to be 7, or neutral. 6.5 to 7.5 is a safe range as well. Higher than 7.5 and you’ll see an accelerated buildup of scale, especially if your water is already hard. Harder water tends to have a higher pH.
  • Sodium
    • High sodium content in your water can sour the taste of your coffee, but it’s usually only an issue when softening hard water, which releases sodium in the process. The target for sodium content is 10 mg/L.


Scale is a white, powdery buildup of calcium deposits left behind by water. Scale can plug up boilers and internal plumbing, reducing heat efficiency and water flow throughout your machine. Most problems with espresso machines are caused by an accumulation of scale. Hard water, high pH water, and high alkalinity all contribute to scale buildup. Certain filters and a diligent descaling schedule will prevent these issues from arising.

Making Brew Water

This is a simplified method that does not require scales, exotic or expensive chemicals or specialized equipment. In fact everything you need you may already have or it’s all available at low cost in most any grocery stores.

You’ll need 2 gallons of distilled water, baking soda, epsom salt, 2 empty 1 liter containers, a teaspoon and half teaspoon measure, a funnel and something to measure milliliters. At the grocery store near us, the distilled water is $0.89/gal., baking soda is $0.99/gal., and the epsom salt is $2.99. From here, we can make a gallon of water for less than ninety cents.

To start, fill each 1 liter container with a liter of distilled water. You can eye it, measure, or weigh it with 1 liter equal to one thousand grams.

Label one bottle “magnesium/hardness” and label the other “alkalinity/buffer.” These bottles will contain concentrates we’ll use to dose our gallon of water.

To the alkalinity/buffer bottle, add a half teaspoon of baking soda. Put the cap on and shake to mix. The baking soda is actually sodium bicarbonate and will dissolve very easily. Be sure you’re using baking soda and not baking powder. To the magnesium/hardness bottle, add two and a quarter teaspoons of the epsom salt. When it’s all in cap and shake. It may take a little shaking and mixing to get it all to dissolve. Epsom salt is Magnesium sulfate and is providing the minerals for our water in the form of magnesium.

The one liter concentrate of magnesium is enough to dose about 15 gallons of brew water and the alkalinity/buffer concentrate will dose about 5 gallons. Next step is to open the gallon of distilled water and pour off 1 cup or 250 milliliters. That is about how much of the 2 part concentrates we’ll be adding back in. Now to the distilled water, add 63 milliliters of the magnesium/hardness concentrate. Then, add 185 milliliters of the alkalinity/buffer concentrate. Using a shot glass, we can fill 3 times to the 60ml line and then another 15ml to get to 185.

With those in, put the cap on, give it a shake to mix and you’re done.