Water filters for coffee machines: 7 must-know facts

Why do I need a water filter for my coffee machine?

We often get asked this, and we wanted to set the record straight.

The bottom line: A water filter is essential for the ongoing health of your coffee machine.

What is a water filter? And what does it do?

The water filters typically used in coffee machines are ion exchange filters.

What is an ion exchange filter? Well, it’s a filter containing resin beads which trap the ions that cause limescale.

What do they do inside coffee machines?

You might be asking, “but how does that actually work?” In which case read on, if you don’t want the science, just skip to the next section.

Calcium and magnesium ions are what cause limescale to build up.

The resin beads in an ion exchange filter start off holding sodium or hydrogen ions.

When hard water passes through, calcium and magnesium ions are drawn to the beads. Because they have a stronger charge, they knock off the sodium or hydrogen ions and take their place.

The calcium and magnesium stay trapped in the filter, and the sodium and hydrogen gets released into the water.

Thus, ion exchange has taken place; limescale doesn’t build up in the coffee machines and your water tastes better.

What happens if I don’t have a filter?

Filters are essential in coffee machines. Without them limescale will build up inside the machine.

This is particularly catastrophic in coffee machines because there are so many intricate internal parts. This makes it hard to remove the limescale inside without using strong, corrosive chemicals. So it is much easier to prevent the limescale build up in the first place.

How often should I replace my coffee machine filter?

About once every 6 months.

How much do they cost?

Office coffee machines require large filters. This is because they process such large volumes of water. You might be surprised to see coffee machine filters that cost upwards of £100, but don’t worry, that’s the industry standard.

Which filter should I choose for my coffee machine?

Your office coffee supplier will most likely offer a big brand like a 3M or a Brita. It’s important to let your supplier handle the distribution of filters, as they will know which one is needed for your coffee machine.