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Jan 17, 2024

How do specialty coffee shops filter water for coffee?

For some time now, the conversation around water quality for coffee has become

For some time now, the conversation around water quality for coffee has become more and more prominent across the global specialty coffee sector. Coffee shops around the world are clearly looking to maximise water quality and consistency. By doing so, they ensure that they are serving the highest-quality beverages possible.

To do this, many coffee shops invest in high-quality water filtration systems. In many cases, their water supply will not be correctly optimised for brewing coffee. Without it, they will struggle to get the best possible flavour profile in the cup.

Depending on their geographical location, coffee businesses may need different kinds of water filtration systems. Moreover, each one may work differently.

To find out more about how water is filtered for coffee, I spoke to two industry experts from Pentair Europe. Read on for more of their insight.

You may also like our article on how baristas can maximise water quality & consistency .

It's often said that filter coffee is 98% water, so it clearly plays an instrumental role in how coffee is extracted. Ultimately, a large part of how your coffee tastes is dependent on the filtered water you use to brew it.

First and foremost, water should always be safe to consume.

However, depending on your location, the chemical composition and mineral content of tap water can vary widely. Tap water contains a variety of minerals in different concentrations, and the presence of some of these can have huge implications on coffee flavour. These include:

Matteo Colamartino is the Product Manager at Pentair Europe, a leading water filtration solutions company.

"Water for coffee needs to be filtered for two main reasons," he tells me. "Firstly, you want to protect your espresso machine and equipment from corrosion or the build-up of limescale, which reduces efficiency.

"Secondly, you want to make sure you get the best results from your coffee," he adds.

In terms of protecting equipment from corrosion and limescale, higher levels of minerals and compounds in water can leave chalky deposits – especially in espresso machine pipes and boilers. This happens when calcium and/or magnesium in water fuses with carbonates, which then creates limescale deposits.

Ronny Billemon is a Foodservice Technical Support and Applications Engineer at Pentair Europe.

"Water which is too hard often causes scaling and corrosion, which can then damage your coffee equipment," he says.

When we talk about hard water, we refer to two different types of hardness: total hardness and carbonate hardness (or temporary hardness). The former is the amount of calcium and magnesium present in water, while the latter is a measurement of the water's levels of carbonates and bicarbonates.

We measure water hardness in terms of parts per million (ppm). The Specialty Coffee Association recommends using water with a total hardness of 50 to 175ppm and a carbonate hardness between 40 and 75ppm. However, if not managed correctly, a total hardness of 100ppm or more can lead to limescale deposits in espresso machine boilers and pipes.

"You want to have an optimal level of these minerals in your water as this will assist with the extraction of your coffee, including oils to enhance mouthfeel," Ronny says.

For example, optimum levels of calcium can lead to a creamier mouthfeel. A balanced amount of magnesium, meanwhile, can enhance sweetness. As a general rule of thumb, the ratio of calcium to magnesium in tap water is around 3:1, which generally reflects the balance of these minerals in natural water sources.

Moreover, if your water is too hard, you risk losing balance and clarity in the cup. Conversely, very low mineral water content could result in your coffee tasting flat, or having a lack of body and structure.

Considering all this, in almost every case, coffee shops can improve the quality of their coffee by using filtered water. However, there are several different types of water filtration systems available on the market. This can make it difficult to know which one is right for your coffee shop.

One of the most basic yet important systems is activated carbon filtration. This method uses an activated carbon filter to remove contaminants such as chlorine, chloramine, and volatile organic compounds (VOC), as well as off-tastes.

"Carbon filtration is at the very core of high-quality water filtration systems," says Matteo. "It removes any compounds which result in off-tastes and odours, and is often combined with particle filtration as part of a single filtration system.

"Pentair's basic Everpure carbon-based filtration system also uses ‘scale inhibition’ technology, which doesn't change the hardness level, but does control levels of limescale build-up," he adds. "In areas with lower water hardness levels, these systems provide a low cost but effective solution to maintain the calcium and magnesium levels in your water."

Reverse osmosis (or RO) removes around 95 to 97% of minerals (or total dissolved solids) from water. This makes it one of the best all-around water filtration solutions. RO is particularly popular with coffee shops in areas which have higher levels of water hardness (around 250ppm or over).

Essentially, the system works by forcing water through a semipermeable membrane at high pressure.

"[Compared to carbon filters], RO systems are at the other end of water treatment, as they allow you to manage all water issues at once," Matteo explains. "They basically remove most of the minerals dissolved in water, however, coffee-focused filtration systems include technologies which re-add minerals back into the filtered water to meet the coffee shop's required levels.

"With continuous fluctuations in the mineral content of tap water, high-performing reverse osmosis systems are ideal," he adds.

In recent years, more and more coffee shops have started to invest in multi-stage filtration systems, which are often specifically designed for coffee businesses to deliver consistent results.

These systems often include a number of filtration steps, including:

Furthermore, they are usually best suited for coffee shops in areas with higher levels of tap water hardness. They also combine the benefits of carbon filtration and ion exchange technology in one cartridge.

"Pentair's multi-stage Claris cartridges remove contaminants and odours, as well as all sediments which are bigger than 0.005mm using the carbon block fine sediment filtration technology," Ronny tells me. "They also include varying levels of water softening technology depending on your tap water quality."

Matteo tells me: "We offer different types of Claris cartridges, such as Standard, Ultra, N, and Prime, which are compatible with different levels of water hardness.

"For example, the Claris Ultra cartridge uses ion exchange and sequestering DuoBlend technology to maintain issues related to scaling and maintain a neutral pH level, as well as reducing the corrosivity of filtered water when using standard decarbonisation filters," he adds. "This means the filtered water has more balance of calcium, magnesium, and other minerals."

In turn, this means coffee shops can achieve more balanced extraction of flavours in their coffee.

Matteo also explains that multi-stage water filtration systems need to protect your equipment.

"The Claris N cartridge has hybrid sodium-softening technology," he says. "This helps to control levels of gypsum (a soft sulphate mineral deposit composed of calcium sulphate dihydrate) in areas with high levels of sulphates in tap water, while also reducing the risk of corrosion.

"The Claris Prime cartridge, meanwhile, combines chloride and sulphate reduction, mineral stabilisation, and corrosion inhibition technologies for long-term protection of your equipment," he adds. "Additionally, the seven-step bypass in the filter head ensures you can reach a certain TDS level in the filtered water."

There are many clear advantages of investing in a high-quality water filtration system for your coffee shop.

Firstly, Ronny explains that filtered water improves coffee beverage quality and consistency.

"If you are focused on serving high-quality coffee, you must consider optimising your water quality," he says. "This can make or break beverage quality.

"Water treatment can also be a significant cost for coffee business," he adds. "However, when you invest in the right solution, you can actually save money and reduce concerns about maintenance and upkeep."

This is because using a water filtration system which best suits your needs, as well as the water quality in your area, will reduce the likelihood of technical issues – and thereby reduce maintenance fees.

"The more limescale that builds up in pipes and boilers, the lower the efficiency of your equipment," Matteo says. "This means your espresso machine requires more energy and more frequent servicing, which increases costs, too."

He also mentions that research from the Water Quality Association suggests coffee shops which use hard water spend 29% more on energy costs than those which use softer water.

Considering the recent rise in food and energy prices for hospitality businesses, finding ways to manage them has never become so important.

Alongside improving coffee quality and reducing costs, another topic that's increasingly being discussed when we talk about water filtration is sustainability – as it is in all aspects of the coffee sector.

"Most RO systems waste up to 90% of incoming water," Ronny explains. "When selecting a RO system, make sure to check for high-performance units which offer at least a 50% water recovery rate – this will make a huge difference to your annual water bill."

Matteo says: "We take the carbon footprint of our filtration systems into account. For instance, the Pentair MRS 600 HE and Conserv E RO systems require up to 50% less energy and water than other models.

"Moreover, their high water recovery technology can reduce water and sewage charges, as well as minimising environmental impact," he adds.

Matteo also explains that making water filtration more sustainable often depends on optimising systems. This involves manufacturers focusing on more realistic solutions when it comes to end of life product solutions, like customers recycling their cartridges.

"It can be a complicated process, but we are looking into more efficient ways to recycle cartridges on a more local level," he says. "We also take into account the level of emissions produced from the transportation of used cartridges from coffee shops to recycling plants."

For many coffee shops, water filtration is an excellent way to ensure that you’re getting the most out of each cup of coffee you serve to customers.

However, knowing which filtration system to use is key. And with different systems offering different results, it's best to start by checking the water quality in your local area.

Enjoyed this? Then read our article on maximising water quality & consistency in your coffee shop .

Photo credits: Ronny Billemon

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Zoe is an expert content marketer based out of the Pacific Northwest. She has a deep-rooted passion for all things coffee with over five years of coffee copywriting and barista experience.