Roomba's flagship robot vacuum handled my house of children and pets and it's 43% off on Prime Day

Beth Mauder/ZDNET

What's the deal: 

The iRobot Roomba Combo j9+ is down by 43% during Prime Day, currently priced at $799.

Also: The best Prime Day deals: Live updates

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ZDNET's key takeaways

The Roomba Combo j9+ is a $1,400 two-in-one robot vacuum and mop with a retractable mop head. During Prime Day, it's $600 off.Its biggest upgrade comes with the Clean Base, which can automatically refill the water tank.
The mopping feature is just passable when tasked with big messes, especially compared to competitors with dual oscillating mop heads.

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The Roomba Combo j9+ has made its way into my rotation of robot vacuums -- and let me tell you, I'm very impressed. It's sleek and has a modern look and feel, and iRobot went out of its way to fix the shortcomings of the previous Combo j7+. The most notable feature is the Clean Base's Auto-Fill Dock, meaning the robot can simply go back to the docking station whenever it needs to refill its clean water tank.

Also: The best robot vacuum mops you can buy

The Combo j9+ is meant to be iRobot's most efficient robot yet, utilizing iRobotOS to map your home seven times faster than before. The robot can automatically label your map with up to 90% accuracy, maintain its P.O.O.P. (Pet Owner Official Promise) guarantee, and do much more. I loved my Roomba j7+ last year but was left wishing for more with the Combo j7+. I now feel like the two worlds collided successfully with the Combo j9+.

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Straight out of the box

I love the high-end look and feel of the Roomba Combo j9+. The robot blends in beautifully with my furniture and isn't a machine that I would tuck away in my laundry room or office so guests don't see it. It is bulkier than its predecessor, but that's because this model has a sturdier, refillable water tank, a drawer that holds the removable dust bin, and storage on the inside to keep additional mop pads. The trade-off is well worth it.

Beth Mauder/ZDNET

The robot's setup process is relatively simple. You'll need to find a suitable place against a wall near an outlet, plug in the Clean Base, and align the robot with the charging port. Pair the device with the iRobot companion app, and you're all set.

Also: The 35+ best Prime Day robot vacuum deals

Next, the mapping run. With the app up to date, it took just a few minutes for the robot to figure out my home's layout. The robot stuck to the walls and edges of the furniture, used AI to try and predict where the rooms were divided, and then labeled them accordingly. I only need to make a few tweaks to the mapping, so it was generally reliable. If you already own an iRobot device and you've created a map of your home, you can transfer the map from one device to another in the iRobot app.

How does the Combo j9+ perform?

When I first tested the robot, I ran it just hours before hosting my family for Thanksgiving because who doesn't live life on the edge? I immediately noticed how much longer the robot took to clean my home than my previous j7+ model. That's not necessarily a bad thing.

The Combo j9+ cleans in smaller, shorter passes as opposed to the longer passes of the j7+. In ways, this lets the robot clean at a finer pace. To show you how much longer it took, the j7+ can clean my living room in 14 minutes while the Combo j9+ takes 30 minutes. This isn't a huge deal when you're just cleaning a room or two, but it made a difference when I cleaned my entire home. 

Also: The best robot vacuums: Expert tested

The biggest difference and most notable improvements come with the Clean Base. The Roomba Combo j9+ can now automatically refill its clean water tank, fixing my biggest gripe with its predecessor. I no longer have to babysit the machine; the Combo j9+ is that self-sufficient. The water tank itself feels sturdy and holds a considerable amount of cleaning solution before refilling.

Beth Mauder/ZDNET

The Clean Base also allows the Roomba j9+ to self-empty as needed, storing the dirt and debris in the disposable bag for about 60 days. Your mileage will vary with this feature; my home with pets and kids will certainly be dirtier than someone's home of two. 

Just as impressive is how quiet the Combo j9+ self-empties. It is noticeably quieter than any of the previous Roomba models; I can run the Combo j9+ while my little one sleeps without worrying that the suction from the auto-emptying will wake him up. I can't emphasize enough how much I love this feature. I can reset my main living spaces in the evening while getting my vacuuming and mopping done. It's a very attractive feature and a must-have for parents with little ones.

Vacuuming performance

For what it's worth, vacuuming has never been an issue for the Roombas I've tested. My home is frequently littered with dirt, debris, pet hair, food crumbs, and more, and I've been impressed time and time again with the suction capability of these robot vacuums. Pet hair is cleaned up efficiently, my rugs and carpets have pretty vacuuming lines, and the space under my dining room table remains crumb-free. 

Also: This one feature could revolutionize the way robot vacuums and mops work

With the Combo j9+, you can choose to have the robot vacuum or both vacuum and mop. If you send the j9+ to a room with just carpet, it somehow knows it will perform a vacuum-only job. Plus, obstacle avoidance is fairly reliable. My cords, pet toys, stray shoes, and everything in between are always left untouched.

Mopping performance

The Clean Base liquid container is equipped to handle iRobot's approved liquid cleaning solution, so that is the only liquid I put in the refillable container. I prefer this over just using water because my floors require something a little more powerful.

While the Combo j9+ won't put your local deep cleaning service out of business, it can keep floors looking tidy enough. During testing, I noticed the longer I went without manually mopping, the more streaks I saw left from the robot. The j9+ applies just enough pressure to wipe off most stains, dirt marks, and other messes, so I've felt comfortable with letting it clean the house during the week while I manually mop on the weekend.

ZDNET's buying advice

I'm thoroughly impressed with the upgrades that came to the Roomba Combo j9+ from the previous model. If you're like me and can do heavy-duty mopping on the weekends, this machine will keep your floors clean between deep cleanings. In a house filled with pets, kids, and everything in between, that's a big win for me.

It certainly helps that iRobot loves to run sales, especially around the holidays, and I've seen this model routinely drop below the $1,000 price point (from $1,400), like right now during Prime Day, available for only $799.