Water for Coffee

Not all water is created equal. And while most of us sip a cup of coffee, bite into a succulent chunk of meat or a crustry, fragrant slice of freshly baked bread; we seldom give a thought to the role water plays in all of these meals and beverages. Within the hospitality and hotel industry, we come into contact with water with every sip and bite. When it comes to coffee and tea for the discerning palate, water can make or break the taste . With the correct water, coffee can produce a full aroma. Whether you’re preparing an elegant espresso or an aromatic mocha with Ethopian Highlands Coffee; top quality water is the basic of most refined beverages.

Does Water Quality Affect the Taste of Your Coffee?

Selecting the right quality of water matters a lot. And while the quality of water varies throughout regions of the world, filtered and tap water are commonly used to brew coffee as they are easily available in most places.

But it’s not just a case of whether hard water (high PPM) is bad and soft water (low PPM) is good. What actually matters is what the dissolved solids are and what they’re doing to the brew that really matters.

Depending on your location, your tap water will have a different mix of minerals such as calcium, magnesium and sodium which will determine whether the water is higher in minerals (hard) or distilled (soft).

When it comes to coffee, roasted beans are full of compounds like citric and lactic acid and eugenol (and we know that you know that dear coffee barristers!) which exist in different variations- giving it complex and varying flavours. Water itself is complex with varying levels of calcium and magnesium which affect the taste of your coffee – and therefore your life…

water for iced coffee

It’s What Inside That Counts

Magnesium and calcium generally make up the bulk of dissolved solids in water and both are beneficial to extraction. Magnesium tends to bring out fruitier more acidic and delicate notes, whereas calcium brings out more chocolatey, creamy, heavy notes. It is important to have a balance of both these minerals when brewing coffee, however, in specialty coffee softer water with higher levels of magnesium is preferred to help promote and nurture complex acidity.

Some hard water compounds tend to be sticky and hang onto compounds in your coffee. If eugenol hangs around, your coffee will have a ‘woodsier’ taste. While magnesium is a sticker compound that delivers a stronger cup of java. Water with a high level of bicarbonate may render a bitter cup of coffee.

High magnesium (hard water) can produce a stronger, more flavourful coffee compared to softened or more distilled water.

Achieving Perfect Water for Coffee

There are various filtration methods used by high-end specialty coffee shops to get softer water. Here are a few of the methods with their pros and cons:

  1. Reverse osmosis (RO)
    1. While RO is a popular filtration method used, it can be expensive. A semipermeable membrane removes unwanted particles and chemicals with more expensive models being able to remineralize the water with important minerals. Without remineralising the water with magnesium and calcium, coffee can end up tasting flat. (Lack of magnesium and calcium however is good for machine health though.) Another downside with RO systems if that for every 1 litre of filtered produced, 1 litre of water with filtered minerals is wasted.
  2. Calcium Treatment Unit (CTU)
    1. This is a popular and more affordable filtration system with the aim to remove calcium thereby preventing a build-up of limescale in your equipment. From a long-term cost perspective, this saves you money, as limescale build-up over time can cause major damage to your coffee making equipment, and therefore damage to your life! A con of CTU’s is that they filter a certain amount of minerals and still produce relatively hard water.
  3. Magnesium-Enriching Filter
    1. One of the latest additions to the coffee offering at Climpson and Sons, original East London Coffee Roasters, is the BWT magnesium enriching filter called Bestmax Premium.

Ask the Experts

Here’s what a UK Speciality Coffee Shop had to say after tasting coffee with 8 different waters:

*Coffee cupping is a coffee tasting technique whereby hot water is poured onto freshly roasted and ground beans directly into the cup and allowed to steep for 3–5 minutes. The infusion is then mixed and the foamy head removed. Coffee needs to cool before tasting allowing for flavours to emerge. Two spoons are used, one going in the cup and the other in the mouth.

Here at Climpson and Sons Cafe, “we cupped ‘The Estate’ with 8 different waters to see if we could notice any difference. We used Evian, Tesco Ashbeck, RO, CTU, Bwt Bestmax Premium, tap water, cupping water and a domestic Brita Filter. It was evident from our custom cupping water and the ‘Bestmax Premium’ that higher levels of magnesium definitely increase acidic complexity and produced some of the favourites on the table.”

“What we like about this product is it has an adjustable bypass, where the level is set depending on the hardness of your water,” says Kieran Lamont of Climpson and Sons Cafe. “It goes through various filtration stages and is then enriched with magnesium. We have had really positive results with this as we know magnesium enhances fruity acidity, which has worked excellently with our morning batch brew as well as producing less harsh, more balanced and sweeter espresso. We’re currently extending our trial of this product to our coffee bar down at Spitalfield’s, so if you’re a regular then let us know if you notice a difference!”

water for baristas

To Mineralise or Not to Mineralise?

Beyond hard and soft water, the contents of the water is what counts. Certain minerals will assist with higher levels of extraction while others will also cause damage to your machines. So when it comes to increasing the lifespan of your espresso machines, it’s advisable to use a filter that decreases calcium content and produces water that’s less than 200ppm or less. Choosing a water that’s higher in magnesium produces a sweeter and more complex brew well suited to the palates of the speciality coffee industry.

BWT’s Perfect Water for Coffee: By Professionals for Professionals​

We keep in touch with baristas and coffee connoisseurs from around the globe so we know exactly what’s important when it comes to preparing coffee. Or every water challenge, we have the water optimisation system for you. Our BWT Magnesium Technology not only enriches the water with taste enhancing magnesium, reduces limescale but it also produces an outstanding cup of coffee.


BWT Bestmax PREMIUM, an innovative filtration system for use in the hospitality sector, optimises water straight from the tap. Any extraneous constituents, including calcium, particles and taste-impairing substances like chlorine, are removed from the tap water. The filter cartridge with its Magnesium Mineralizer technology enriches the drinking water with precious magnesium to create perfect-tasting hot drinks.


Whatever your water needs and the desired quality of your water, we can assist you at a commercial and industrial level. Contact us here for all your water treatment solutions: https://bwtafrica.com/contact-us/