iRobot Roomba Combo J9+ review: a commendable hybrid robot vac with swappable mops

Welcome to T3's review of the new iRobot Roomba Combo J9+, a robot vacuum cleaner that also mops the floor using replaceable mops fitted to an auto-retracting mopping mechanism that raises whenever the robot’s camera and sensors detect carpet or rugs.

It’s all been a bit quiet on the iRobot front recently so it’s good to see the US-based company back with another sterling autonomous floor-cleaning bot... even if there isn’t a massive difference between the new Roomba Combo J9+ we’re looking at here and its stablemate, the cheaper Roomba Combo J7+.

The Roomba J9+ is available in three configurations: this 2-in-1 Combo version with self-emptying Clean Base and onboard water reservoir for automatic refilling of the robot’s mop reservoir; the non-mopping J9+ with standard self-emptying Clean Base; and the basic J9 comprising just the robot vacuum and no mopping or automatic bin emptying function.

I should add at this juncture that having a self-emptying dock is always a good thing for pet owners because it means you won’t have to empty the bot’s tiny onboard dustbin yourself every 10 minutes or so. Instead it will trundle back to its Clean Base docking station where all detritus in the robot’s titchy bin will be sucked into the dock's much larger dust bin that’s already fitted with a disposable bag. All you have to do is periodically – say once a month – interject by throwing away the dock’s full bag and replacing it with a new one. All very hands-free, in other words.

So let’s get down to the nitty gritty and see how well the Roomba Combo J9+ performs at both vacuuming and mopping, and whether it should soar to to the top of our guide to the best robot mops money can buy.

iRobot Roomba Combo J9+ review: price and availability

As of writing, the iRobot Roomba Combo J9+ is available in the UK direct from the iRobot store, priced at a knockdown £899. However you can also expect it to hit amazon.co.uk pretty soon.

If you’re shopping Stateside for the Roomba Combo J9+, consider iRobot’s US store where it retails at $1,399.99 or Amazon US where you can snap it up for 99 cents less.

iRobot Roomba Combo J9+ review: design

The  J9 robot itself is as elegantly styled as any of its predecessors and comes with just one button on top to start, pause or resume a cleaning session. Nevertheless, pretty much everything to do with the J9 bot is controlled via the accompanying iRobot app which I will discuss further below.

The robot itself is 32.5cm in diameter though the two centrally-mounted ribbed rubber rollers are only 17cm in length and that means only 17cm of floor space is vacuumed at any one time. Like the majority of robot vacs, the J9 is also equipped with a spinning side brush on the right which should normally fling dust and debris along skirting boards into the path of its suction portal. However, its circular shape means that some dust will inevitably remain in most corners of a room – par for the course with all circular robot vacs.

At 40.5cm in height, 41cm in width and 31cm in depth, the Combo J9+’s Clean Base is quite a bit bigger than its predecessor, the J7+, and I’m not so sure about the design of the thing. For a start, the ribbed cladding isn’t as attractive as that on the standard vac-only J9+. It just looks more incongruous in situ and it isn’t helped by the plastic faux wooden top which feels cheap. If iRobot’s designers were aiming to turn the Clean Base into some kind of side table, I don’t think it’s worked out particularly well. Also, the shiny black section of plastic just in front of the fake wooden plinth tends to attract dust like a magnet.

iRobot Roomba Combo J9+ review: vacuum features

The new Roomba Combo J9+ comes with a smorgasbord of features, including three levels of suction power and automatic Carpet Boost mode. iRobot fails to list how many Pascals of power the J9 robot has, preferring instead to say that it has ‘100% more suction power’. I expect it to be in the region of 5,000 to 5,500Pa – the Roborock S8 Pro Ultra is rated at 6,000Pa – which is easily powerful enough for the majority of real-world cleaning scenarios.

Rather cleverly, the J9 also features Dirt Detective, a self-learning software add-on that remembers where the dirtiest parts of the home are. The idea is that it will clean the dirtiest rooms first while adjusting suction power and mop scrubbing motions in the process. It seemed to work very well in my tests.

iRobot Roomba Combo J9+ review: mop features

Like most hybrid robot vacs, the Combo J9+ is fitted with a static, rear-mounted wet mopping pad that drags along the floor while picking up dust and even tackling both wet and dried stains. However, the majority of cheaper vac mops are not able to discern the difference between hard floors and carpet and those that can will simply avoid carpet altogether.

Roborock was one of the first manufacturers to feature a vibrating rear mop that raises a few centimetres whenever the robot’s sensors detect carpet. It works remarkably well in most instances. Conversely, iRobot has opted for a more dependable method for raising its mop whenever the vac-bot is on carpet. Consequently, its whole mopping plate retracts outwards and upwards so it comes to rest on top of the unit. This means it is impossible for the mop to dampen even the deepest of carpets.

However, unlike the the Roborock S8 Pro Ultra and several other contenders which feature a fully hands-off mop-cleaning docking base with reservoirs for both clean and dirty water, the Roomba Combo J9+’s mop attachment requires manual cleaning by removing it and either rinsing it under a tap or popping it into the washing machine.

As an owner of the excellent Roborock S8 pro Ultra and its predecessor, the S7 MaxV Ultra, I never mind getting down on my knees with a damp cloth to clean their filters, mop cleaning mechanisms and trays, especially since I only do it every couple of months or so. I also never mind having to empty the smelly contents of their dirty water containers into the loo every couple of weeks, followed by a rinse under the tap. 

If the thought of handling mucky parts covered in pet hair and a stinky water tank gives you the heebie jeebies, then the iRobot system would likely be your best bet. There is no mess involved with this system, especially if you just lob the dirty mop into the washing machine. Simply remove the dirty mop and fit the second one that comes in the box, and perhaps buy a few extra mop heads as backup.

iRobot Roomba Combo J9+ review: navigation

iRobot prefers to use a front camera and sensor system for navigation instead of LiDAR. The downside to this is that it takes much longer for an iRobot vac to initially map a home than, say, a Roborock which uses LiDAR for near instantaneous room mapping. On the plus side, a non LiDAR model like the J9 will happily punch through a bed or sofa valance and clean underneath while most LiDAR-navigated robots will see the valance as an impenetrable wall.

After turning on the J9 and syncing it to my home wi-fi – a doddlesome process – I tapped the ‘clean everywhere’ option on the app and off it trundled. Now, my downstairs area is entirely open-planned so I expected the J9 to have no problems in navigating and mapping the whole living space. What I didn’t anticipate was the time it took to perform the task. 

For some reason the J9’s first run completely omitted the kitchen and hallway. In fact, it stayed in the lounge and dining areas without going through the hall doorway or even the wide space into the kitchen. On day two it did much the same thing, though it did venture into three feet of the hallway before retreating again. I checked the map on the app and, sure enough, it had only mapped the lounge-cum-dining area.

Day three was cause for celebration because the bot finally ventured into both the hall and the kitchen and when I checked the map, there they were. All I had to do was move or delete some automatically generated boundaries so I could name each room individually. The moral of the story is to let the bot do its thing in its own time – and this pretty much applies to most camera-based robot vacuum cleaners. 

Once full mapping had been completed, I commanded the J9 to clean the entire ground floor and it performed one of the longest and most extensive cleaning regimes I’ve ever come across. Very impressed. Mind, I should add that the J9 does bump into walls and obstacles a lot though it does do it gently – but not gently enough to avoid light scuffing on the robot’s outer casing.

One of the J9’s best navigation facets is its ability to avoid obstacles like wires, toys and even dog poo and not run slipshod over them. Its Genius Home Intelligence software plays a big part in this because there’s a bank of images like wires, socks and several styles of doggy poo in its database so it can easily recognise different objects as it approaches.

iRobot Roomba Combo J9+ review: Clean Base

In addition to automatically emptying the contents of the robot’s onboard dustbin into the dock’s bigger bagged bin, this model’s Clean Base is also equipped with a large water reservoir that automatically tops up the robot’s own tiny water container that sits just above its internal bin. This means you don’t have to keep filling the robot’s water tank which is the case with its cheaper sibling, the Combo S7+. However, as mentioned above, this charging dock doesn’t come with any kind of mop cleaning mechanism so you will need to fit a fresh mop and clean the dirty one yourself.

It’s not really a negative, but all robot vacs’ self-emptying systems are really noisy and none can hold a candle to the J7+ for sheer ear-shattering volume. It’s a relief to say that the Combo J9+’s Clean Base is about a thousand times quieter and far less high pitched. In fact, I’d say that it’s the quietest self-emptying process of any robot vac I’ve ever reviewed. Well done to iRobot’s designers – you clever little sausages.

According to iRobot, you should get at least a month’s worth of muck and hair into the Clean Base’s disposable bag and you won’t need to hunt around for another one because the spare is stored neatly in an inside door compartment.

iRobot Roomba Combo J9+ review: vacuum performance

This robot vac is an exceptional performer. I’d say that it's among the very best for picking up both fine and oversized debris like breakfast cereals. I genuinely have zero qualms about its vacuuming behaviour and I’m equally impressed by how well it navigated my hard floor rugs – at no time has it tangled itself up in tassels.

Crucially, it has also ventured under the valance of my sofa and given everything a good sweep beneath. Yes, its navigation can be a bit erratic but that’s the case with all robot vacs – you never know where they’ll go next.

iRobot Roomba Combo J9+ review: mopping performance

The first thing to note about all robot vac mops is that they can’t clean up large spills like porridge and other large liquid messes. This is because they simply drag a wet pad around behind them. Yes, the J9 will definitely clean a dried stain or some muddy footprints by moving back and forth over it but it will likely smear larger spills across the floor. If you want a machine that cleans up most heavy spills effectively, buy a best hard floor cleaner like the superb Eufy MACH V1 Ultra which I rate very highly indeed.

In my various mopping tests the J9 performed remarkably well. I was particularly impressed by its back and forth motion which deftly eradicated the muddy paw prints left by my two Labradors. However, since I have engineered wood flooring, I set the amount of water administered to the mop to its lowest possible level. This is because the mop leaves a damp stripe behind it which may or may not cause long-term warping issues on wooden flooring, especially those of the laminated variety.

Conversely, if you have tiled, Linoleum or polished concrete floors, set the mopping in the app to medium or full wetness and rest safe in the knowledge that everything will look spick and span without having to reach for that oh-so-last-century option, the old-fashioned mop and bucket.

iRobot Roomba Combo J9+ review: iRobot app

iRobot’s app interface is pretty easy to navigate though there are a few anomalies. Take mapping, for instance. Normally it’s best to initially select a ‘mapping’ run when you first run the bot. This is so the robot can use all its battery energy to map the whole home in one go without any vacuuming or mopping. Although the ‘mapping only’ function is available in the app, it’s buried in a submenu.

Also, as alluded to above, mapping in the iRobot app is generally much more basic than Roborock’s system which allows the user to add furnishings like tables, cupboards and pet beds, and even create full 3D maps of the home that you can rotate to see from any angle. Roborock’s maps are also much more detailed, with defined edges of a room and all obstacles clearly identified. By contrast, the iRobot app’s map is less comprehensive though sufficient enough for users to customise with room boundaries and ‘keep out’ zones, etc.

iRobot Roomba Combo J9+ review: verdict

iRobot has adopted a different method to the norm with this new 2-in-1 model. Yes, it still automatically empties the contents of the robot’s onboard dustbin, but instead of washing the mop after every cleaning session, you simply pop the dirty mop in the washing machine and instal a fresh one. This method avoids having to empty stinky dirty water containers and getting down on hands and knees to scrub the dock’s mop cleaning system.

I personally don’t mind a bit of grubby hands-on cleaning but if you’re after a more sanitary method of autonomous mopping as well as efficient vacuuming, the iRobot Roomba Combo J9+ is an excellent place start.