Behind the Scenes: How Starbucks Filters Their Water To Make Sure Every Cup of Coffee is Perfect - Filter Flair

If you're a fan of coffee then no doubt that you will have definitely heard of Starbucks. Love them or hate them, Starbucks are the largest coffeehouse chain in the world so it's safe to say they know a thing or two about making a great tasting coffee. So, how does Starbucks make sure every cup of coffee is perfect?

You're probably thinking "well, it's got to be down to the coffee beans they use...", and you're not wrong. No doubt about it, getting a great tasting coffee needs high quality, flavourful coffee beans. But one thing that's often overlooked is the main ingredient - WATER! We know that most coffee beverages are made up of up to 98% water, so it's absolutely critical that the water used is of an equally high standard.

The Finest Coffee Beans + Poor, Low Quality Water = Poor, Low Quality Coffee.

For coffee to taste its best, the water used to brew it must be clean, balanced and great tasting which is why Starbucks is known to operate a triple stage water filtration system.

Starbucks Tweet that they filter water in store

This blog post will discuss the most common water filtration systems used in coffee shops, as well as looking at Starbucks' unique water filtration systems and why it has been chosen for ensuring they only use the best tasting water for each and every coffee.

Best Water for Coffee

Clear, chlorine-free water with a pH of 7 and a reasonable concentration of minerals makes the best water for making coffee (around 150 TDS). These qualities in drinking water encourage the strong flavours and fragrance production and efficient flavour extraction. 

Since water makes up 98% of coffee, the water chemistry in your brew will significantly impact the coffee's appearance, fragrance, and flavour. Chlorine and chloramines may give the coffee an unpleasant chemical aftertaste and smell, and the subtle nuances of the coffee bean won't be extracted if your water is too soft, resulting in a flavourless brew.

There are many different types of coffee shop water filter systems, but all of them work to achieve the same goal: to remove contaminants from the water before it goes into the coffee machine.

Some of the most common contaminants and factors that can affect the taste and quality of coffee are: 

  • chlorine 

  • mineral content

  • pH

  • bacteria 

Common Coffee Shop Water Filter Systems

Using a coffee shop water filter system, you can ensure that the water that goes into your machine is clean and free of these contaminants.

Here are the most common filters used by coffee shops:

Ion Exchange (Limescale Reduction) Filters

For professional results, often a professional solution is needed which is why many coffee shops turn to ion exchange filters, which are specially developed to reduce limescale whilst also filtering water through carbon for chlorine and contaminant reduction.

This multi-stage process is highly effective and typically these filters come with a fixed or variable bypass that allows a set percentage (usually 30%) of water to bypass the ion exchange stage, providing the optimal mineral content to be retained in the water without the negative impact of limescale.

The most popular ranges of these filters are:

These are the most common filter systems we find being used across the UK and for good reason. Providing the best tasting beverages and reducing machine downtime and damage should be at the forefront of every coffee shop owners mind, and these systems from the leading brands deliver just that.

Carbon/Limescale Inhibiting Filters

Aside from Ion Exchange filters, for areas where limescale isn't a problem often an activated carbon filter with integrated limescale inhibitor will be enough to achieve the best results. Carbon filters are highly effective in removing chlorine from water and enhancing its flavour, whereas the limescale inhibitor offers protection to the machine by stopping limescale from building up within it, which is a common cause of machine breakdown and costly downtime.

Common filters used for this include:

Everpure Silver Cans

Omnipure Q & ELF Range

3M AP2 Range

These types of filters tend to be less bulky and are more cost effective than ion exchange filters and often with higher capacities. The downside however is that they offer less control than is possible with many ion exchange systems and as they aren't necessarily set to the specific water conditions on site.

Calcium Treatment Units (CTU)

Calcium Treatment Units, often called CTUs, is a no-frills approach to softening water however certainly still effective.

CTUs remove hardness minerals from water to prevent limescale, whilst also improving the taste of incoming feed water with activated carbon filtration, making them popular for use with equipment such as espresso machines, combination ovens, water boilers, and vending machines.

Rather than using traditional sodium ion exchange as is used in water softeners, CTUs use a hydrogen ion exchange process to ensure water remains drinkable.

Starbucks' Water Filtration System: 3 Stage Filtration System

Whether it's a flat white or soy cappuccino, each and every Starbucks coffee is brewed with high-quality water that has been through a 3 stage, triple filtration process consisting of sediment and activated carbon filtration as well as water softening where needed.

This technique successfully removes impurities and particles from the water, ensuring the water used in every beverage is purified, great tasting and perfect for coffee and hot drinks.

How Does Starbucks' Water Filtration System Work?

The three way filtration system used by Starbucks is very versatile, allowing different types of filter cartridges with varying benefits to be used all in one system.

The standard set up of the three-stage filter system are as follows:

Stage one: At this stage, preliminary filtration occurs. A sediment filter removes suspended particles, such as silt, rust, dirt, etc., from water. This level of water filtration safeguards the carbon filter while enhancing the water's appearance and flavour.

Stage two: Chlorine and other pollutants are eliminated in the second stage of the three-stage filter system. This is why activated carbon-containing carbon filters are employed. Besides removing chlorine and chloramines, the carbon filter also prepares the water for further filtration.

Stage three: The final stage filter varies depending on water conditions on site but most often this will consist of a water softening cartridge to reduce hard water-causing minerals and minimise limescale build up.


If you've ever struggled to replicate your Starbucks coffee at home, now you know how they do it. With water making up to 98% of a coffee, you really can't afford to neglect the most important ingredient. Whilst a similar filtration system can be set up at home to achieve similar results, even water filtered through just a simple carbon filter will make a big improvement to the quality of your water. Who would have thought, you don't need to be a barista to make a great tasting coffee!

Want to know which filter system is best suited for you to make the perfect coffee at home? Get in touch with our team and give your coffee the boost it needs!

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