after descaling, my coffee tastes terrible, like vinegar or chemicals, even after running several water cycles.

Diagnosis

The chemical taste, often described as vinegary or metallic, is caused by residual lactic or citric acid from the descaling agent trapped within the internal hydraulic circuit of the De'Longhi Magnifica Evo ECAM29043SB. While the machine prompts for a rinse cycle, the internal tubing and the brew group assembly often retain small pockets of concentrated solution that are not fully evacuated by the standard automated rinse. This happens because the descaling agent is denser than water and can settle in the "dead zones" of the thermoblock or the brew group's infusion chamber. If the rinse cycle was interrupted or if the water tank was not filled to the maximum level during the flush, the chemical concentration remains high enough to contaminate the first 10-20 cups of coffee. You can confirm this by tasting a cup of hot water dispensed from the steam wand; if it tastes sour or acidic, the residue is still present in the main boiler.

How to Fix It

To fully neutralize the system, you must perform a manual deep-flush of all three primary water paths: the steam circuit, the coffee dispensing spouts, and the brew group.

1. Fill the water tank to the maximum fill line with fresh, filtered water. Ensure the tank is seated firmly to avoid air locks.
2. Place a large container (at least 1 liter) under the steam wand and the coffee spouts.
3. Turn the steam dial to the 'ON' position and dispense hot water continuously for 60 seconds. This clears the thermoblock and the steam pipe where descaler often pools. Turn the dial back to 'OFF'.
4. Press the 'Long Coffee' button repeatedly. Run this cycle 5 times in a row without adding coffee beans. This forces a high volume of water through the brew group and the delivery spouts, flushing out any trapped chemicals in the infusion chamber.
5. Run the 'Espresso' cycle 3 times. This ensures the smaller apertures and the coffee outlet channels are completely purged.
6. Empty the drip tray and the coffee grounds container, as the descaling residue often settles in the waste area and can create a lingering smell that affects the taste of the brew.
7. Refill the tank one last time and run one final 'Long Coffee' cycle to ensure the water is crystal clear and tasteless.

If That Didn't Work

• Remove and Wash the Infuser: Turn the machine off and unplug it. Open the side door and press the two red release buttons to remove the brew group (infuser). Rinse it thoroughly under warm running water without using soap. If the descaler leaked into the brew group housing, it can leave a film on the plastic that tastes like chemicals. Let it air dry for 10 minutes before reinserting.
• Clean the Water Tank Gasket: Remove the water tank and inspect the valve at the bottom. Sometimes descaling solution clings to the rubber gasket or the float magnet. Wipe the bottom of the tank and the receiving area in the machine with a damp cloth to remove any dried chemical crystals.
• Deep Clean the Milk Carafe (if applicable): If you have the lattecrema system, run the "Clean" function three times. Descaler can migrate into the milk circuits during the process, and the milk proteins can bind to the chemical residue, making the taste persist longer.
• Perform a Hard Reset: Power the machine off at the wall for 30 minutes. This allows any trapped air bubbles in the thermoblock to settle, ensuring that the next flush of water moves through the system more efficiently and pushes out remaining residues.

Heads Up

• Avoid Vinegar: Never use white vinegar for descaling the Magnifica Evo; the acetic acid is too aggressive for the internal seals and leaves a pungent smell that is nearly impossible to remove. Only use De'Longhi's official Eco-Decalcifier.
• Water Quality: If you use very soft water, reduce the frequency of descaling to avoid unnecessary chemical exposure to the internal components.
• Rinse Thoroughly: Always fill the water tank to the absolute maximum during the rinse phase. If the tank runs dry during a rinse, the machine may prime with air, leaving pockets of descaler trapped in the pipes.
• Brew Group Lubrication: After washing the brew group to remove chemicals, if you notice the machine struggling or making a grinding noise, apply a small amount of food-grade silicone grease to the sliding rails.