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Below is the order I’d actually check, from most common to least.
1. The dirty water tank (the obvious one)
If your Roborock has a mop function with two tanks, this is where most of the funk lives. Dirty mop water sits in the tank between runs, bacteria multiplies, and a few days later you’ve got that distinctive swampy smell.
The fix is mostly just emptying it after every run, not at the end of the week. We have a whole article on this:
If you’ve already done the dirty-tank routine and your Roborock still smells, keep reading. The smell is coming from somewhere else.
2. The mop pads (the one most people miss)
This is the one that got me. The mop pads stay damp for hours after a cleaning cycle, and if they don’t dry out properly between runs they go full mildew. You can usually smell it if you pull a pad off and sniff it directly — it’s a wet-dog, musty kind of smell, separate from the swampy water-tank smell.
A few things that helped:
- After each run, peel the pads off and hang them somewhere they can actually dry. Leaving them stuck to the underside of the robot in a humid dock is the worst possible place for them.
- Wash them in the machine every week or two. Most are machine-safe, just skip the fabric softener (it kills absorbency).
- Replace them. Mop pads are consumables. Once they start smelling even after a wash, they’re done. I keep a stack of these 10-pack replacements around — they fit a huge range of Roborock models (Qrevo, Q Revo S/Pro/Plus/MaxV, Saros, Curv, Edge, etc.) and at ~10 pads for the price of one or two OEM pads it’s not really worth trying to nurse old ones back to life.
If you only do one thing on this list, swap the pads. That alone fixed maybe 70% of the smell for me.
3. The dustbin and filter
Less common, but worth checking. If you’ve vacuumed up anything wet (a damp spot on the floor, a bit of pet food, crumbs that the mop then re-wetted) it can sit in the dustbin and start to smell. The HEPA filter can also pick up moisture and go funky.
- Empty the dustbin and give it a rinse with warm soapy water. Dry it fully before putting it back.
- Tap out the filter. If it looks grey/yellow or smells when you sniff it, replace it. Filters are cheap and they don’t recover once they’re saturated.
4. The base station / dock
If you have an auto-empty or self-wash dock, this is its own ecosystem. The dirty water it pumps back into the dock tank is doing the same swampy thing as the on-robot tank, just out of sight. The wash tray underneath (where the mops get rinsed) also collects grime.
- Empty and rinse the dock’s dirty water tank daily if you can, every other day at minimum.
- Pull out the wash tray and clean it weekly. There’s almost always a film of brown gunk you didn’t know was there.
- Run a dock self-clean cycle with a splash of white vinegar in the clean water.
5. Hit everything with an antibacterial spray
Once you’ve cleaned the parts, give the inside of the dustbin, the wash tray, and the underside of the robot a quick spray with an antibacterial / odor-killing spray and wipe it down. The smell is mostly bacteria, so actually killing the bacteria (vs just rinsing it around) makes a real difference.
I use this one — works on fabric and hard surfaces, no harsh bleach smell, and it doesn’t leave a sticky residue on the plastic. A couple of sprays on the mop pads before they go into a wash also helps.
Habits that stop the smell coming back
Once you’ve reset it, keeping it neutral is mostly about not letting water sit anywhere for long:
- Empty the dirty water tank (and the dock’s dirty tank) at the end of every run, not later.
- Pop the mop pads off and let them dry between runs. Or rotate two sets so one is always drying.
- Use filtered or distilled water if you have hard water — the mineral residue helps bacteria stick.
- Wipe down the wash tray weekly.
- Replace mop pads and filters when they stop coming clean. They’re consumables, not lifetime parts.
A Roborock that gets this routine basically never smells. Mine hasn’t in over a year. Skip the routine for a week or two and you’ll be right back to the swamp.
