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Quick answer: Your Eufy’s dirty water tank smells because used mop water sits in the Clean Station’s wastewater tank and grows bacteria. Empty it after every run, run the dock’s self-clean mode with a splash of vinegar, and make sure the mop pads fully dry before the next run. On the X10 Pro Omni and S1 Pro, the hot-air dryer needs enough time to finish — if you’re running back-to-back cleans, damp pads are the main smell source.
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, Eufy’s spinning mop pads (used on the X10 Pro, X9 Pro, and S1 Pro) stay damp inside the dock after a wash cycle. Even on models with hot-air drying, running the robot before the pads fully dry brings the smell back.
Fixes by model
X10 Pro Omni and S1 Pro — spinning disc 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: press the release button on the side of the Clean Station, slide the tank out, empty it, rinse it under warm water, and slide it back in. Do this after every cleaning session.
X9 Pro — spinning pads, no hot-air dryer
The X9 Pro doesn’t have hot air, so the pads need to air dry naturally. After the self-clean cycle finishes, peel the pads off the robot and set them somewhere they can dry completely before the next run. Empty and rinse the wastewater tank each time.
Older models with rectangular pads
Same principle: empty the wastewater tank after every run, dry the pads between cleans, machine-wash them every week or two without fabric softener.
Self-clean with vinegar
Add a teaspoon of white vinegar to the clean water tank and trigger a self-clean cycle from the EufyClean app — or press the button on the dock directly. The cycle flushes vinegar through the mop wash system and into the wastewater tank. Empty the wastewater tank immediately after the cycle finishes. For a harder reset, wipe the mop-washing tray and the interior dock surfaces with an antibacterial spray after emptying.
Keep a set of Eufy-compatible replacement mop pads on hand for when washing no longer clears the smell.
For the full source-by-source walkthrough that covers every robot mop brand, see Robot Vacuum Dirty Water Tank Smells Bad?
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?
Press the release button on the side of the Clean Station to slide the wastewater tank out, empty it, rinse it under warm water, and slide it back in. Do this after every cleaning session — it's separate from the dust bag.
Can I put vinegar in my Eufy robot vacuum?
Yes. Add a teaspoon of white vinegar to the clean water tank and run a self-clean cycle — the vinegar flushes through the mop wash system and deodorizes the dock tray and wastewater tank. Avoid foaming soaps.
My Eufy X9 Pro still smells after I cleaned the tank — why?
The X9 Pro has no hot-air dryer, so the pads need to air dry naturally between runs. If you're running back-to-back cleans without drying time, mildewed pads are the smell source. Peel them off after each session, let them dry fully, and replace them when washing no longer clears the smell.
