You run the robot. The floor looks damp when it is done. But drag your finger across it an hour later, and it still feels greasy. Or you notice the same bit of grit that was there before.
Most people assume that is just what robot mopping is. It is not. It is what happens when the mop design has not moved on from the first generation of robot vacuums.
eufy HydroJet was built around a different question: not how do we add a mop to a robot vacuum, but why does mopping fail — and how do we fix that specifically.
Why Robot Vacuum Mopping Usually Disappoints
There are two main mop designs on the market, and understanding each one helps explain what HydroJet is doing differently.
Flat pad mops press a damp cloth against the floor using the robot's weight. There is no active scrubbing. The pad picks up dirt in the first room, carries it to the second, and drags it across the third. By the end of a run, debris has been redistributed more than removed.
Dual-spin mops are a genuine step forward. Two rotating disc pads generate real friction against the floor, and high-speed rotation combined with downward pressure makes a noticeable difference on everyday mess. For many households, this works well.
Where HydroJet goes further is in how the mop handles what it picks up. In any mop design where the pad surface is not continuously cleaned during the run, dirt accumulates on the mop itself. The mop that starts on your kitchen floor and the one that finishes in the hallway are not the same mop. HydroJet's rolling design was built specifically to solve that.
HydroJet 1.0: Fixing the Core Problem First
HydroJet 1.0 started with the mop itself rather than the station.
The rolling mop continuously cleans itself as it moves. Dirty water collects into a separate tank. Fresh water feeds the mop surface from a clean reservoir. At any point during the run, the part of the mop touching your floor is working from a clean surface.
Three things change when the mop stays clean throughout:
1. No cross-contamination
The kitchen debris does not travel to the hallway. What the mop picks up goes into the dirty water tank, not back onto the next room's floor.
2. Dirt is removed, not smeared
A clean mop surface lifts particles rather than pushing them around. The floor is cleaner at the end of the run than at any point during it.
3. Far fewer interruptions
Because the mop cleans itself continuously, it only needs one wash-back during a full cleaning session, roughly every 55 minutes. No repeated stops. No waiting cycles between rooms.
HydroJet 2.0: Three Specific Upgrades
HydroJet 2.0 keeps the self-cleaning rolling mop and builds on it in three directions.
Upgrade 1: Closer to the Edge
The rolling mop now extends 15mm beyond the robot body when running along walls. That gap matters. The strip where the floor meets the wall collects dust and dried spills more than anywhere else in a room. Most robot mops do not reach it at all.
Upgrade 2: Cleaner to the Floor
Two changes here, each addressing a different part of what clean actually means.
First, pressure. Downward force increased from 10N to 15N in the 2.0 version. At 15N, the mop actively scrubs the floor surface rather than sliding across it. This matters most in kitchens and dining areas where grease and dried food stick to tiles.
Second, the water itself. The S2 generates electrolysed water on board, producing hypochlorous acid and ozone. Both are natural disinfectants used in food-safe cleaning environments. The results are TUV certified:
- 99.99% water sterilisation rate, sustained for 5 days
- 99.99% floor sterilisation rate
- Eliminates bacteria as small as 3 microns
Upgrade 3: Stronger Self-Cleaning
The 2.0 version adds a second squeegee strip to the mop cleaning mechanism. The first strip scrubs. The second strips remaining dirty water and diverts it before it can drip back onto the floor. Combined with 32 uniform water injection holes across the 29cm mop width, every part of the mop surface stays evenly supplied with clean water throughout the run.
What HydroJet Feels Like to Use
In the kitchen after cooking
The mop applies 15N of pressure across the tile surface. Grease that a damp cloth would smear gets lifted. The water on the floor is sterile. You are not walking back in to find a faint film left behind.
In a mixed-floor home
When the robot moves from hardwood to carpet, the mop lifts 28mm automatically. The carpet stays dry. When it returns to hard floor, the mop comes back down and picks up where it left off.
Along the skirting boards
The mop extends outward as the robot tracks the wall, which means the strip at the base of the wall gets mopped on every pass, not skipped because the mop could not reach.
After the run
The robot returns to the station. The mop washes at 60 degrees C, the temperature needed to break down grease properly. A turbidity sensor checks whether the wash was enough. If the mop is still dirty, the station runs a second cycle without being asked. Then 55 degrees C hot air dries it fully before the next run. No wet mop sitting in the station overnight.
Which eufy Models Come Equipped with HydroJet
HydroJet is a core mopping technology across the eufy robot vacuum range, developed across two generations.
HydroJet 1.0
Equipped on:
- eufy Robot Vacuum S1 Pro: 8,000 Pa with 3D obstacle avoidance system
- eufy Robot Vacuum E28: 20,000 Pa suction power with portable deep cleaner
- eufy Robot Vacuum E25: 20.000 Pa suction power focusing on floor cleaning
- eufy Robot Vacuum C28: 15,000 Pa suction power
These models share the same self-cleaning rolling mop design: continuous dirty water collection, a clean water reservoir feeding the mop throughout the run, and wash-back only once per 55 minutes of cleaning. If you are choosing between them, the differences come down to navigation system, suction power and station features — HydroJet itself works the same way across all four.
HydroJet 2.0
Equipped on:
- eufy Robot Vacuum Omni S2: 30,000 Pa with CleanMind AI system
The 2.0 generation adds three upgrades to the 1.0 foundation:
- The dynamically extending mop that reaches the walls much closer.
- Electrolysed water for TUV-certified 99.99% floor sterilisation.
- A dual-squeegee mechanism that prevents dirty water from returning to the floor.
- Downward pressure also increases from 10N to 15N.
If you are deciding between a HydroJet 1.0 and 2.0 model, the difference comes down to how much you prioritise edge coverage, floor hygiene, and self-cleaning strength. For everyday hard floor maintenance, 1.0 is a meaningful upgrade over conventional mop designs. For homes where kitchen hygiene or thorough edge cleaning matters, 2.0 takes it further.
Explore more eufy robot vacuum S2 features that fit your home.
Frequently Asked Questions
What is eufy HydroJet?
HydroJet is eufy's rolling mop system for robot vacuums. Unlike flat pads or spin mops, it cleans itself continuously during the run, collecting dirty water into a separate tank so the mop surface stays clean from the first room to the last.
What is the difference between HydroJet 1.0 and 2.0?
HydroJet 1.0 introduced the self-cleaning rolling mop and dual water tank design. Version 2.0 adds three upgrades: a mop that extends 15mm closer to walls, a downward force increased from 10N to 15N for deeper cleaning, and a dual-squeegee mechanism that stops dirty water from dripping back onto the floor.
Does the HydroJet mop lift when it reaches carpet?
Yes. On models equipped with auto-lift, the mop raises automatically when carpet is detected, keeping the carpet dry throughout the cleaning run.
Is HydroJet 2.0 hygienic?
Yes. Electrolysed water generates both hypochlorous acid and ozone, achieving a 99.99% floor sterilisation rate — independently tested and TUV certified. Additionally, the mop self-cleans at 60°C in the station after every run, preventing bacterial buildup on the mop pads.
Which eufy robot vacuums have HydroJet?
HydroJet 1.0 is equipped on the eufy Robot Vacuum S1 Pro, E28, E25 and C28. HydroJet 2.0 launches with the eufy Robot Vacuum Omni S2.
