Coffee shops around the world have a simple mission: serve delicious coffee to customers to make sure they keep coming back, time and time again.

And while using high-quality beans is of course a vital part of this, many coffee shop owners unwittingly ignore one key component of the beverages they serve: water. 

Water makes up around 98% of every cup of coffee, and plays an instrumental role in extracting soluble flavour compounds. Good-quality water helps you achieve a balanced cup profile, while poor-quality water can have a detrimental effect on the aroma and flavour of your coffee.

So, how can café owners ensure they are using water that is suitable for brewing coffee? I spoke to four professionals to find out more.

Interested in the World Coffee Championships? Learn more about how Pentair supports them here.

What is water hardness?

Tap water contains a significant amount of minerals and compounds. The specific makeup will vary heavily depending on where in the world you are. These compounds come from soil, water treatment facilities, and water supply systems.

The term “hardness” is typically used to describe the amount of minerals that water contains, but there are two types of hardness.

Ronny Billemon is Pentair’s Area Sales Manager for Benelux & the Nordics. He explains the first type: total hardness. “Total hardness [is] the amount of scale minerals (calcium and magnesium) present in the water,” he says.

Magnesium and calcium help extract flavours from coffee, but an imbalance of these minerals will lead to under or overextraction.

“Carbonate hardness, however, [is the measurement of] the amount of carbonates or bicarbonates present in the water, [but] not all are linked to hardness,” Ronny adds.

Carbonate hardness is also referred to as “temporary hardness”. When water boils, carbonate minerals migrate out and accumulate on surfaces (such as kettles or boilers). This means the water loses minerals. It is also why your kettle needs to be descaled. 

However, we do want some carbonates in our water. They act as acidity buffers for coffee by controlling the pH balance of water. The ideal pH range for brewing coffee is between 6 and 8.

Nigel Pask is a Key Account Manager at Pentair. He tells me that ideal water hardness levels can vary.

“Water standards depend on whether you are a barista looking to optimise the quality of the coffee served, or the equipment supplier looking at minimising water-related issues.”

For brewing, the SCA recommends using clean, fresh, and odour-free water with a total hardness of 50 and 175 parts per million (ppm – a measurement of milligrams per litre). Carbonate hardness should be between 40 and 75ppm. 

“Generally, baristas will follow the established SCA guidelines, [while] equipment manufacturers will set limits based on the detrimental effects [water hardness] may have on equipment – the two may not be the same,” Nigel explains.

Why does water hardness vary?

Water hardness levels differ around the world – even within individual countries. For example, in Australia, average hardness levels are around 100ppm in southern cities like Melbourne. However, further west in Perth, the average is over 500ppm.

Nigel says: “Water quality and hardness depend on the topography and geology of the area around the water source.

“Water is [extracted] from either the ground (pumping out of naturally formed wells/reservoirs) or from surface water (rivers, lakes, and reservoirs).”

He tells me that this creates differences in water hardness. “Typically, ground water will be harder than surface water as it has permeated through and dissolved multiple layers of [bedrock],” Nigel says. “The type of rock it passes through [dictates] the level and type of hardness.

“Surface water can still be hard depending on the geology of the ground it passes over. However, it also tends to be higher in sediment and organic materials, which can impact taste and colour.”

Water treatment systems vary across the world. The process of treating water also adds compounds into the water, as Nigel explains.

“Additional effects on quality are often ‘manmade’,” he says. “For example, chlorine and chloramines are used for disinfection and multiple contaminants from agriculture, industry and general life.”

While he notes that “many of these are trace elements” which “do not significantly affect the operation of a coffee shop”, some of these compounds can affect taste and damage equipment. 

“For instance, iron chlorides can have a severe impact on equipment,” he says. “[They] tend to be more [prevalent] in coastal areas.”

What does this mean for brewing coffee?

“Purifying” water for coffee brewing isn’t as simple as removing these minerals and compounds. While too many in your water will inhibit even extraction, too few will have the same effect. Ultimately, water hardness should be balanced to ensure the best possible experience when brewing coffee.

“We know that higher levels of calcium and magnesium improve the quality of extraction,” he says. “However, higher levels of carbonates block the [finer] elements, aromas, and flavours [released] from coffee.”

If your water is low in both total hardness and carbonate hardness, your coffee will underextract, tasting sour and weak. High total hardness but low carbonate hardness will create heavy and dull flavours in the cup.

In contrast, water with low levels of total hardness and high levels of carbonate hardness will taste chalky and flat, lacking complexity. If total hardness also increases to high levels, the coffee will be easily overextracted.

The best thing to do is to reach an optimum level of both.

Filtration systems help balance water hardness to desirable levels. Gerben Hettinga is the owner of KoffieDok in the Netherlands, who import and resell coffee and water filtration equipment, including Pentair’s Everpure RO systems.

“There are multiple reasons why one would choose a filtration system for their coffee equipment,” Gerben says. “In a perfect world, that would depend only on tap water quality and target mineral composition.”

However, it’s not just water quality that café owners should focus on. Filtration systems can help to protect water-intensive equipment, such as espresso machines and filter brewing machines.

“If the conclusion is that the tap water will harm your coffee and/or equipment, it will be an investment in your product rather than [an] expense,” Gerben says. “It also helps to calculate the cost per cup of a filtration system.

“Aiming for good water is usually beneficial to the longevity of the equipment, but some elements like chlorine can be a serious challenge.”

When it comes to choosing the best filtration system for a coffee shop, the decision will largely depend on water quality in the local area.

“With the wide range of Pentair Everpure filtration solutions, coffee shop owners can achieve the optimal balance between water quality for coffee extraction and equipment protection,” Ronny adds.

Improving water quality

There are a number of filtration methods that coffee shops can use to improve water quality.

Activated carbon filtration can remove some of the compounds in water, but has little to no effect on the mineral content. Ion exchangers, however, can be used to add or remove minerals from water. They also give users the option to re-add minerals if needed.

However, in the long term, the most efficient way to balance hardness levels in water is to invest in a high quality filtration system.

Nigel says: “For soft water, solutions such as the Pentair Everpure BH² filter system will reduce chlorine levels, reduce particulates as [small] as 0.2µm, and ensure the water is free of off-tastes and colours.

“Where hardness is the key issue, the Pentair Everpure Claris Ultra range will not only reduce hardness levels, but also offer stable pH levels, as well as offering some protection against potential corrosion.”

Nigel also tells me that when mineral or hardness or levels are particularly high, or when there are contaminants present that regular cartridge-based filtration systems can’t deal with, Pentair offers reverse osmosis systems. 

Reverse osmosis is a method of water filtration that uses a semipermeable membrane. This membrane allows water to pass through at high pressure, and removes minerals to meet the required hardness levels. 

Among baristas and café owners, reverse osmosis is widely considered the most effective filtration method for achieving optimum water hardness levels.

How can you test your water?

Considering that water hardness levels vary, cafés should check their water and understand how it might be affecting extraction. It’s easy enough to do this in many cases – just check with your local water treatment facility or supplier.

Bart Deprez is the co-owner of Viva Sara Coffee in Kortrijk, Belgium and chair of the World Coffee Events board.

“It seems our tap water composition has changed a lot over the years. Other elements in the water are causing more technical issues with out equipment,” he says.

“In Belgium, you can go online to the website of the water company and get a detailed water report,” he adds. “It is easy to [access] and provides all values you would like to know about [hardness levels].”

Gerben, however, says that café owners can use equipment to quickly assess hardness levels themselves.

“In the Netherlands, every water supplier publishes detailed water specs online. By comparing the TDS (total dissolved solids) in your tap water to these levels, you can check if you are using the right source,” he says. “There are [areas] in the Netherlands that don’t need filtration, while other parts do.”

Ultimately, looking into which filtration solution you need for your coffee shop is the first step you should take. 

“The support of focused experts [like] the Pentair team is of high value,” Bart says. “It helps you understand the chemistry and source the correct water treatment solutions.”

This expertise has been reflected by the announcement that Pentair will be the global water sponsor for the 2021 World Coffee Championships (WCC). 

Originally slated to take place in Taipei, the 2021 championships (including the World Barista Championship, World Brewers Cup, and World Cup Tasters Championship) will now be held at HostMilano 2021 from October 22nd to October 26th.

Bart concludes: “When you have specialty coffee on the menu, you won’t get quality results in the cup if your water quality is not sufficient. Getting the right support is a must for delivering great quality drinks.”

No matter how high-quality your coffee is, making sure your water is within optimal hardness ranges is incredibly important when brewing high quality coffee.

To start, coffee shop owners can assess the water hardness and quality in their area. This will give you a better understanding of the systems and solutions that are most appropriate for your coffee business.

Enjoyed this? Then read our article on testing water in pursuit of excellent coffee.

Photo credits: Ronny Billemon, Pixabay, Coffee Geek

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Please note: Pentair is a sponsor of Perfect Daily Grind.

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