Descaling your espresso machine at home

Descale an espresso machine when the flow slows down. A machine that pulled a 25-second shot when new and now takes 35 seconds with the same grind setting has mineral buildup narrowing the waterpath, and dissolving that buildup takes about thirty minutes with the right solution. Hard-water areas might need this monthly. Soft-water areas can stretch to three months. The process is the same for most machines, with a few Breville and DeLonghi specifics worth knowing.

Scale buildup inside the machine

Tap water carries dissolved calcium and magnesium. When water is heated inside the boiler, these minerals precipitate out of solution and form a hard, chalky deposit called limescale. It accumulates on the heating element, along the internal tubing, and around the valves and seals. Over time, it narrows the passages water flows through, reduces the machine's ability to hold temperature, and introduces a flat, chalky taste into the espresso.

The rate of buildup depends entirely on your water's hardness. Water above about 120 mg per litre (ppm) of hardness, measured as calcium carbonate, is generally classed as hard, and it scales a machine faster. Daily brewing with hard tap water can produce visible buildup in four to six weeks. With soft or filtered water, the interval stretches, but some minerals always remain and scale still accumulates.

Longer shot times are the usual first sign, and they are easy to blame on technique. Adjusting the grind to compensate hides the problem, while a descale cycle brings the shot time back to where it was on day one.

Recognizing the signs

Four reliable indicators: slower flow rate, longer brew times, a taste shift toward flat or chalky, and the descale warning light (if your model has one). The warning light counts brews or tracks elapsed days, so it is an approximation calibrated for average water hardness. Hard-water households may need to descale before the light turns on.

If you would rather work to a schedule than watch for symptoms, use these intervals. For daily use with moderately hard water, every two to three months. For very hard water, monthly. For soft or filtered water with lighter use, every three to four months.

The right solution and why vinegar is wrong

Three options work. Commercial descaling solutions from espresso machine manufacturers (Breville, DeLonghi, Sage, Jura all sell their own) are formulated to dissolve calcium without damaging rubber seals or aluminum components. They cost several times more per dose than plain citric acid.

Citric acid powder, available from grocery stores or online for a few dollars, is the active ingredient in many commercial descalers. A tablespoon dissolved in a litre of water does the same job at a fraction of the cost. It is food-safe, rinses clean, and leaves no odour.

White vinegar is the suggestion that will not die, and it is wrong for espresso machines. Acetic acid is weaker than citric acid at dissolving calcium carbonate. It requires a stronger concentration to work. It leaves a persistent smell that survives multiple rinse cycles. And it can degrade certain rubber gaskets over time. A machine that smells faintly of vinegar three rinses later will make coffee that tastes faintly of vinegar, and the only fix is more rinsing. Citric acid or a commercial solution avoids the problem entirely.

The general process

Fill the water reservoir with the descaling solution mixed according to its instructions, or one tablespoon of citric acid per litre of water. Run about a third of the solution through the brew group by starting a brew cycle with no portafilter and no coffee in place. Let the machine sit for 15 to 20 minutes with the solution inside so it can dissolve the accumulated scale. Then run the remaining solution through.

After the solution is gone, fill the reservoir with fresh water and run at least two full tanks through the machine to rinse out residual descaler. Taste a small amount of the rinse water before brewing coffee. If it tastes clean, the rinse is done. If there is any acidic or chemical note, run another tank.

Check your machine's manual before starting, because some models have an automated descale mode that controls pump timing and rinse cycles for you. Following the automated sequence when one exists is easier and more thorough than doing it manually.

Breville and Sage specifics

Breville machines (sold as Sage in the UK and Europe) typically have a dedicated descale mode activated through a button combination described in the manual. On machines with a steam wand, the cycle sends solution through the wand as well as the brewing path, so both branches of the water system get treated. The "clean me" light on the Barista Express calls for the cleaning cycle, a backflush with a cleaning tablet, which is a separate job from descaling.

Breville sells pre-dosed descaling sachets sized for the reservoir. On a machine still under warranty, follow the manual on which descaler to use.

DeLonghi specifics

DeLonghi machines, including the Magnifica and Dinamica lines, have an automated descale program activated through the control panel. The program runs the solution in stages, pausing between them to let the solution sit in the boiler. The whole cycle takes about 30 minutes and the machine prompts you through each step with indicator lights or screen messages.

DeLonghi's branded EcoDecalk solution is lactic acid based, and DeLonghi recommends it for all its coffee makers over citric acid descalers, so on a DeLonghi the branded product is the safer choice. The automated cycle manages the timing and tells you when to add fresh water for rinsing, which removes most of the guesswork.

After the cycle

Run a throwaway shot of espresso and taste it before making one you plan to drink. One wasted puck of coffee is cheaper than a cup that tastes like descaler, and it confirms the rinse was thorough. Empty and rinse the drip tray, which collected descaling solution during the cycle.