Descaling Your Coffee Machine: When, Why, and How

Scale is calcium and magnesium deposits that build up inside your coffee equipment every time you brew. If you are using tap water, it is happening right now. If you have never descaled your machine, there is probably a calcified maze coating the inside of your boiler, blocking your heating element, and slowly strangling your water flow. I learned this the hard way when my first espresso machine died at 18 months because I never once descaled it. That was a $400 lesson I am going to help you avoid.

How Often Should You Descale?

The answer depends entirely on your water hardness. If you are using the mineral water recipe I recommend, you may only need to descale every 6 to 12 months. If you are using hard tap water (above 150 mg/L hardness), you should descale every 4 to 8 weeks. Most machines have a descale indicator, but do not rely on it blindly. Some are based on brew count rather than actual scale accumulation.

What Descaler to Use

Citric acid is my go-to descaler. It is food-safe, effective, inexpensive, and available in bulk online. Mix 20 to 30 grams per liter of water. It dissolves scale effectively without the harsh chemicals found in some commercial products. I buy a 2-pound bag for about $10 and it lasts me over a year.

Commercial descalers from brands like Urnex (Dezcal) or your machine manufacturer are fine alternatives. They are more expensive but pre-measured for convenience. Some contain additional surfactants that help lift deposits in hard-to-reach areas.

Step-by-Step Descaling Process

This process works for most single-boiler and heat exchanger espresso machines. Dual-boiler machines may have specific procedures in their manual.

Step 1: Dissolve your citric acid in the water tank. Use warm water to help it dissolve faster. Fill the tank to full capacity.

Step 2: Run about a third of the solution through the group head by pulling blank shots (no coffee). Let the solution sit in the boiler for 15 to 20 minutes. This soaking time is critical since the acid needs contact time to dissolve scale deposits.

Step 3: Run another third through the steam wand. Open the steam valve and let the solution flow through. The steam system is often where the worst scale buildup occurs because of the higher temperatures.

Step 4: Run the remaining solution through the group head again to flush through any loosened deposits.

Step 5: Fill the tank with fresh water and run the entire tank through the machine, splitting between the group head and steam wand. Repeat with a second tank of fresh water. This thorough rinse ensures no citric acid remains in the system.

Prevention is Better Than Cure

The best approach to scale is preventing it in the first place. Using filtered or controlled-mineral water dramatically reduces scale buildup. A simple inline filter on your water line or a Brita-filtered pitcher can make a significant difference. If you combine good water with regular cleaning routines, your machine will last a decade or more without scale-related issues. Take care of your equipment and it will take care of your morning coffee.