“When people talk about water it gets very complicated, but it should not be.” That is how Gwilym Davies opened the workshop in Prague, about the importance of water. His co-speaker Luca Pompei, Nuova Simonelli representative, added the perspective of an espresso machine manufacturer to the mix.

Water for coffee with Gwilym Davies

Neither of them is an expert in water chemistry so the goal of the workshop was to use their experience in the field to make the complicated topic more practical for baristas and cafe owners. The article below describes the most important findings we took away from the hour-long event.

Two major things to look at in water

As with any other field, you can get easily lost in the amount of data and the complexity of the topic. Rather than giving up or trying to understand everything, it is better to identify the key characteristics that have the major impact on the longevity of coffee machine and the taste of your coffee. These two characteristics are total hardness and total alkalinity.

Total hardness

Total hardness influences the extraction efficiency and the amount of scale inside of your machine. “This is basically the amount of stones in the water, the minerals in the water,” explains Gwilym Davies. If the total hardness is low, you don’t have the “power” to extract your coffee. If the total hardness is high, you will get stones inside of your machine.

“Total hardness is a measurement of the cations in water and can be created by minerals with a positive charge. The primary components of hardness are calcium (Ca++) and magnesium (Mg++) ions. “ – Dissecting SCAA’s Water Quality Standard.

Total alkalinity

Total alkalinity influences the buffering of coffee acids and the corrosion. “If you don’t have enough, your machine will corrode. The water will eat your machine,” explains practically Gwilym. And on the contrary, if you have too much alkalinity, you won’t have that much of acidity in your coffee.

“Total Alkalinity is a measurement of the concentration of negative ions in the water. Alkaline compounds such as bicarbonates (such as baking soda), carbonates, and hydroxides remove hydrogen ions (H+) and lower the acidity of the water.” – Dissecting SCAA’s Water Quality Standard.

What is the right range?

Next question we would obviously ask is, what the right range to have our water measures in is. The specific recommendation may vary but based on SCAE “core zone” for espresso machines and hot water boilers, the range is as below (and in the graph):

Total alkalinity: 40 – 60 mg/L — ppm CaCO3
Total hardness: 55 – 110 mg/L — ppm CaCO3

Water for coffee with Gwilym Davies

What water is coming from your tap?

The best option for you to know the parameters of your water is to request a water analysis with your water supplier or to send the water samples to a lab. These solutions are very accurate but rather time-consuming, hence quite complicated if you need an immediate water test at a cafe environment.

The go-to method of testing water has been TDS and as such, it is a great way to monitor the consistency of the water supply. However, the cheap TDS meters are not accurate enough to provide realistic numbers.

To really get an idea of the total hardness and the total alkalinity, Gwilym brought an inexpensive testing kit that was kindly given by Brita but he said they were easily purchased on Amazon in “water treatment kits for aquariums” category. Costing around 10 euros each, these drop kits will give you an instant insight into your water supply. By adding drops of a solution to your water, its change in colour will determine the level of the total alkalinity and the total hardness.

Choosing the right filtration system

Once you know the parameters of your tap water, you can identify what changes are required and what filtration system you need to purchase. Great tap water can save you a significant amount of money, and subsequently, choosing the right filtration system then can cut the required investment.

The list of filtration systems is sorted by its complexity and the purchase price:

Use Ion Exchange if the goal is to reduce the total hardness ($)
Use Carbon Filtration if the goal is to reduce the total alkalinity ($$)
Use Reverse Osmosis if the goal is to reduce both the total alkalinity and the total hardness. ($$$)

If you have an ‘add back in’ system to find out the possible combinations of hardness and alkalinity you can have, draw a line on the graph from your tap water figures to the point of origin i.e. zero hardness & zero alkalinity.

“Before choosing your filtration system, figure out first what water is coming from your tap, find out what sort of water you want and then find the filtration system that delivers that,“ sums up the whole thought process Gwilym Davies.

And remember, there is no “ideal” water. It depends on: your coffee, the brew method, and your customer taste preferences.