How to remove limescale from tap water and make better coffee or tea?

What is limescale and where does it come from?

Limescale on your coffee maker, tea kettle, carafes and water glasses is a hard chalky deposit, consisting mainly of calcium carbonate. It is the result of hard tap water which is very rich in minerals like calcium and magnesium. Statistics reveal that 85% of European homes are affected by such issues.

This hard water contains above average levels of dissolved minerals (TDS). And while hard water and limescale isn’t dangerous, it could be very annoying and contribute to poor taste.


How does limescale influence my coffee?

Water is an important part of your coffee brewing experience. After all…

Coffee is 98% water.

With that said, the SCAA standards state that for a superior quality coffee extraction, your water should be clean, fresh, odor-free, clear in colour, and should have a maximum mineral content of around 150 parts per million (ppm), while the best water pH for coffee is 7.0 (neutral).

Notice it does not have a specific kind of water or filtering process, just general ranges. This isn’t a life or death scenario here. In other words, it’s safe to use tap water for coffee. It just might not taste that great. For those who are not overly scientific about the process, a general rule of thumb for the water you use in your coffee is to use water you actually like to drink.

But if you want to take it one step further and make your coffee taste even better, you need to better than ‘drinkable water’. Okay, so you don’t have to use a water filter in coffee making. But there are many benefits to finding a good balance to your water (as you probably have guessed, if you’re still reading this).

Also, it’s no secret that water can ruin your coffee equipment. An overabundance of minerals (which are not bad for your coffee itself – in moderation) can build up and wreak havoc on your equipment. Cleaning your machines can be a good idea, but distilled water for coffee machines, or other proper filtration options for your coffee water, can also be a preventative of future chaos.

How do I remove the limescale from my tap water?

There are several methods to remove limescale from tap water including

Conventional softeners:

Removes calcium and magnesium and replaces it with sodium. This is good for preventing scale build up but not so good for your health.

Reverse Osmosis:

The most complete method to reduce limescale uses a membrane with very small holes to filter only water and block chemicals and dissolved solids like calcium, magnesium, lead, arsenic and more. 

The Osmo, the smart 5+ stage home water purifier from Osmosys uses an improved version of the reverse osmosis technology to purify your water and reduces limescale building extremely efficiently. 

Ion Exchange: 

Generally uses cation resins that are strong acid/strong cation (SAC) resin beads to reduce hardness levels and increase sodium levels by removing scale-forming calcium (Ca2+) and magnesium (Mg2+) ions. 

Scale inhibition filters:

These filters do not use scale removal, but employ scale inhibition to help keep your kettle clean. These filters use a phosphate-based chemical to pre-react with the hardness in an attempt to stop the formation of limescale. The water will generally taste more like the water from a carbon filter, but won’t usually give as good of a performance in preventing limescale as other options.

Magnetic / Catalytic / Ionization Devices:

These are magical magnets sold in hardware stores and on social media that claim to soften the water with the magnetic force. Lab testing of these devices have generally shown that they don’t work.

What are the benefits of a limescale water filter?

If you live in an area with hard water and limescale like Barcelona the benefits of limescale water filter include:

  • No more limescale in the coffee pot or tea kettle
  • No more limescale in carafes and glasses making them difficult to clean
  • Better tasting coffee, tea and drinking water 
  • Your coffee maker and appliances that require water last longer and require less maintenance


In summary

  • Limescale is the result of hard water formed by calcium and magnesium
  • There is no proven negative health impact of hard water or limescale
  • Revere Osmosis is the most efficient and complete technology to eliminate limescale in your home
  • The Osmo uses the latest smart water filtration technology to keep your tap water free from limescale all the time

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