Diagnosis
The sour or chemical taste you are experiencing is caused by residual concentrations of citric acid or lactic acid (depending on the descaler used) remaining within the internal hydraulic circuit. In the De'Longhi Dinamica Plus ECAM37095TI, the descaling solution passes through the thermoblock heater and the brew group assembly. If the final rinse phase was interrupted, if the water tank was not filled to the "MAX" line during the rinse, or if the machine suffered a power flicker during the cycle, pockets of concentrated solution remain trapped in the dead-ends of the piping.
This is not a mechanical failure, but a chemical residue issue. The "sour" note is the acidity of the descaler, while the "chemical" taste is the surfactant used to prevent scale from re-depositing during the process. You can confirm this by running a small amount of hot water into a glass; if the water has a slight viscosity or a pungent smell, the circuit is still contaminated.
How to Fix It
To fully purge the system of chemical residues, you must perform a manual deep-flush of the entire hydraulic path. Follow these exact steps:
- Empty the water tank completely and rinse it with fresh tap water to ensure no descaling solution remains on the walls of the container.
- Fill the tank to the absolute maximum line with filtered or fresh cold water.
- Place a large vessel (at least 1.5 liters) under the coffee spouts and the hot water/steam nozzle.
- Using the touch display, select the "Hot Water" function. Allow the machine to dispense the entire tank of water through the hot water spout. This flushes the thermoblock and the primary boiler.
- Refill the tank again. This time, instead of using the hot water function, brew 4 to 6 "Long" coffees (without coffee grounds). To do this, ensure the bean hopper is empty or the brew group is bypassed, or simply run the "Rinse" cycle from the settings menu multiple times.
- Perform a "Steam Purge": Turn the steam dial to the "On" position for 30 seconds to clear the milk frothing circuit, as solution can often settle in the steam wand assembly.
- Empty the drip tray and the coffee grounds container, as the rinse cycles will have filled them with chemical-laden water.
If That Didn't Work
- Replace the Water Filter: If you use the De'Longhi water filter (located inside the tank), the filter medium may have absorbed the descaling solution and is now slowly leaching it back into your coffee. Remove the filter, rinse the tank, and install a brand new filter cartridge.
- Clean the Infuser/Brew Group: Remove the brew group assembly from the side of the machine. Rinse it thoroughly under lukewarm running water. Sometimes the descaler reacts with old coffee oils on the piston, creating a residue that tastes sour. Dry it completely before re-inserting.
- Deep Clean the Milk Carafe: If you use the automatic milk system, run the "Clean" cycle for the milk carafe three times. The chemical solution can migrate into the milk valves via back-pressure during the descaling process.
- Perform a "Hard Reset" Flush: If the taste persists, fill the tank with a mixture of 50% water and 50% white vinegar (only once), run one cycle, and then follow with three full tanks of plain water. This neutralizes the specific alkaline residues some commercial descalers leave behind.
Heads Up
- Always use only the official De'Longhi Eco-Decalcifier. Third-party vinegar or high-concentration citric acid can erode the rubber seals in the ECAM37095TI, leading to internal leaks.
- Never interrupt the descaling cycle once it has started. If the machine asks for more water, fill it to the MAX line immediately; under-filling the tank during the rinse phase is the primary cause of chemical taste.
- Ensure your drip tray is emptied immediately after descaling. The acidic solution can corrode the metal components of the tray if left to sit for several days.
- Check your water hardness settings in the menu. If set too high, the machine will prompt descaling too often, increasing the risk of chemical buildup in the pipes.