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Quick answer: A Eufy dirty water tank smells because used mop water sits in the Omni Station’s wastewater tank. Empty and rinse it after each mopping job, rinse the detachable cleaning tray, and let the pads or roller finish drying. Use only water or the Eufy cleaning solution approved for your exact model.
The X10 Pro Omni, X9 Pro, S1 Pro, and X8 Pro Omni all work differently enough that the fix depends on which model you have.
Where the smell comes from on Eufy
Eufy’s omni docks have two separate outputs — a dust bag for dry debris and a wastewater tank for dirty mop water. The wastewater tank is tucked into the Clean Station and easy to ignore because the dock handles everything automatically. That tank fills with every run and turns sour fast if you don’t empty it.
On top of that, damp mop material creates a separate musty odor. The X10 Pro Omni and X9 Pro use rotating pads, while the S1 Pro uses a roller mop. Running the robot again before the pads or roller finish drying brings the smell back.
Fixes by model
X10 Pro Omni — rotating pads with hot-air drying
These docks run a hot-air pad-drying cycle after the mop wash. It takes 2–4 hours depending on your settings. In the EufyClean app, go to your robot’s settings and check that Mop Drying is enabled and set to enough time. If you’re running the robot daily, schedule it in the morning so the pads have the rest of the day to dry before the next run.
To empty the wastewater tank on the X10 Pro Omni, lift it out of the station, open it, empty it, and rinse it thoroughly with running water. Eufy’s manual also calls for rinsing the detachable mop-cleaning tray. Do this after each mopping job instead of waiting for the full prompt.
S1 Pro — roller mop
The roller, scraper area, and cleaning tray all stay wet. Remove hair from the scraper, rinse the washable tray, and use the drying control. If the roller still smells when dry, replace it rather than repeatedly perfuming the clean tank.
X9 Pro and older pad models
The same principle applies: empty the wastewater tank after every mopping job, use the model’s drying cycle if equipped, and air-dry removable pads when they are still damp afterward.
Clean the station without vinegar
Use the Eufy Clean app’s mop-wash or station-cleaning control with clean water or the Eufy cleaning solution approved for the model. Do not add household vinegar or a foaming cleaner to the clean tank. Remove the detachable tray and rinse it separately, then empty the wastewater tank when the cycle finishes.
Keep model-matched Eufy X10/X9 pads, S1 rollers, bags, and filters on hand for when washing no longer clears the smell.
If the tank is clean but the odor remains, use Eufy Mop Smells Bad? 6 Causes & Fixes to check the pads or roller, tray, dust bag, filter, and brush.
Frequently Asked Questions
Why does my Eufy X10 Pro Omni dirty water tank smell?
The Clean Station's wastewater tank fills with dirty mop water every run and grows bacteria if you don't empty it regularly. The spinning mop pads also stay damp after the wash cycle — if the hot-air dryer doesn't have enough time to finish before the next run, they add mildew smell on top.
How long does the Eufy X10 Pro mop drying take?
The hot-air drying cycle on the X10 Pro Omni and S1 Pro takes around 2–4 hours depending on your setting in the EufyClean app. Make sure Mop Drying is enabled and give it enough time before scheduling the next clean.
How do I empty the Eufy X10 Pro Omni wastewater tank?
Lift the dirty tank out of the Omni Station, open and empty it, rinse it thoroughly with running water, and reinstall it after it drains. Rinse the detachable mop-cleaning tray as well. Do this after every mopping job.
Can I put vinegar in my Eufy robot vacuum?
Do not add vinegar unless Eufy explicitly approves it for your exact model. Use clean water or the Eufy solution listed in the manual, and hand-clean the removable wastewater tank and tray.
My Eufy X9 Pro still smells after I cleaned the tank — why?
Check the rotating pads and cleaning tray. Either can stay damp and smell independently of the wastewater tank. Let the drying cycle finish if equipped, air-dry pads that remain damp, and replace pads that still smell after washing and drying.
