De'Longhi Dedica EC685: No Water Flow
The EC685 has three independent causes for total water flow failure — and one of them is completely silent. The drip tray overflow float sensor cuts the pump without any warning light. This guide covers all three in diagnostic order.
⚡ Quick Fix — 3 Steps
- Check the drip tray first. The EC685 has a float sensor in the drip tray. When the tray fills to capacity, the machine silently disables the pump — no light, no alarm. Remove, empty, and reinsert the drip tray even if it appears not full. The float can trigger early if tilted.
- Check the water tank and seal. Remove the tank, rinse the rubber seal at its base, and reseat firmly. The EC685 tank uses a gravity-feed valve — a partial seal creates enough air ingestion to cause pump cavitation and apparent no-flow.
- If pump runs audibly but no water appears: thermoblock scale blockage. Run a full descaling cycle. If flow does not restore after descaling, the thermoblock passage requires a 30-minute citric acid soak — see procedure below.
Technical Detail — Not In the Manual
The Dedica EC685 drip tray float is a passive magnetic sensor. The float rises on a vertical guide post as the tray fills. At maximum capacity (approximately 350ml), the float magnet aligns with a reed switch in the machine base and cuts the pump relay. This happens with no user notification of any kind. De'Longhi does not document this behavior — the manual simply says "empty the drip tray regularly" with no explanation of consequences. In practice, users who let the tray fill completely assume the pump has failed.
Thermoblock Soak Procedure (Severe Scale)
The EC685 uses a thermoblock rather than a traditional boiler — water passes through a narrow heated channel machined into an aluminium block. The channel cross-section is approximately 3–4mm diameter. Scale accumulation in a 3mm passage causes near-total flow restriction at a fraction of the mineral buildup required to cause the same effect in a 300ml boiler.
- Mix a stronger descaling solution: 2g citric acid per 100ml for this soak (slightly above normal EC685 operating concentration, but acceptable for a single therapeutic application).
- Fill the tank with 500ml of this solution. Run the machine until approximately 100ml has passed through, then power off.
- Allow the solution to sit in the thermoblock for 30 minutes. The dwell time allows acid to dissolve scale deposits in the narrow passage rather than flushing straight through.
- Power on and run the remaining solution through.
- Immediately run two full tanks of fresh cold water as flush cycles.
- Test flow rate. If still restricted, repeat the soak procedure after a 24-hour wait.
For the full De'Longhi EC685 maintenance protocol, see the De'Longhi Maintenance Guide. For the descaling sequence with button codes, see the EC685 Descaling Guide.
FAQ
The EC685 pump makes noise but no water comes out even with an empty drip tray. What next?
If the drip tray is confirmed empty and the pump runs audibly without producing flow: air lock. This occurs when the tank runs fully dry and air enters the thermoblock inlet. Fix: fill the tank completely, remove the portafilter, and run the machine in steam mode for 20 seconds — the steam circuit shares the thermoblock and the pressure from the heating element will often push the air lock through faster than the pump alone can manage. Then switch back to brew mode and test.
How do I know if the EC685 pump has actually failed vs. a blockage?
A failed pump is completely silent when the brew button is pressed — no motor sound, no vibration. A blocked thermoblock produces audible pump noise (vibration/hum) without water output. A pump that has lost pressure produces a weaker, higher-pitched sound and very slow drip output. After a full descaling and soak cycle, if the pump is audibly running at normal volume but still producing no flow, the pump check valve may have failed. The EC685 pump is a ULKA EP5 (same as the Gaggia Classic Pro) and replacements are available for approximately $20–25.
CoffeeFixManual provides independent technical information. Not affiliated with De'Longhi.