The how and why of descaling your coffee machine

If I had a dollar for every coffee machine boiler or valve I have scraped copious amounts of lime scale out of, I wouldn’t need to be writing this post. Scale is in your water, it gives your coffee a little more taste. But it builds up on surfaces, elements and valves and blocks them, decreasing water flow rate and eventually complete blockage.

Some water sources contains more lime scale than other water sources. The amount of scale in water is descried as its hardness and is in fact it’s alkalinity. Lime scale is alkaline by nature and is composed of compounds like calcium carbonate, calcium bicarbonate, silicon dioxide (sand), iron oxide and elements like calcium, magnesium and iron.
When water is heated it becomes reactive and the scale is deposited on the hot components of the coffee system like the elements and all things in a thermal connection to it. I have noticed that the coffee machines worst effected by scale are those that sit at temperature not being used. So turn your machine off at night to avoid scale build up.Steam boilers act as distilling units, leaving the scale behind, so steam boilers are often full of scale.

So what’s our weapon against scale? – frequent de-scaling with an acidic agent (usually citric acid). The idea is dissolve lime scale and flush it out of the system. The problem is that most people do not perform de-scaling correctly or often enough. The frequency with which you descale will depend on the hardness of your water and the running time of your coffee machine. But I recommend monthly.

1. If possible descale your machine when cold. Fill the tank completely with descaling solution.
2. Pump descaling solution through the system until its coming through on the rinse cycle and steam function.
3. Leave the solution sitting in the system for twenty minutes (longer of you have time) and pump the solution out and fresh solution in. Again leave the fresh solution sitting in the system. The idea is to leave fresh solution sitting in the boiler pump etc for time to dissolve scale and then flush it out.
4. When you have run all the agent through, repeat the process with fresh water to remove all of the scale solution.
Make a few shots to clear all the scale out.