iRobot Roomba S9 Robot Vacuum Review

The iRobot S9 is very well-built. Its D-shaped body, similar in profile to that of the Neato Botvac D7, is made of high-grade plastic, accented with a matte-finish copper lid. Its dirt compartment feels mostly sturdy, though its bottom feels somewhat flimsy and could break if dropped. It comes out of the box ready to use, with no assembly required except for setting up its dock station.

This vacuum is pretty easy to maintain.

• Dirt compartment: The dirt compartment is found under the copper bin lid. It features a built-in carrying handle and a release button to open the bottom of the compartment and drop any stored debris. Aside from releasing debris, you can clean it by tapping it against the side of a garbage bin or washing under water. You need to remove the filter before doing so since it isn't washable.
• Filter: The filter is located inside the vacuum's dirt compartment. You can tap it against your garbage bin to dislodge any stuck-on debris, though this component isn't washable, and you shouldn't clean it with water. Like most other parts here, it needs to be cleaned once or twice a month, depending on if you're a pet owner.
• Brushrolls: The brushrolls are accessed by removing the brush guard under the vacuum. You can clear stuck debris or hair wraps by hand once or twice a month, depending on use. It can be a little hard to reinsert the brushroll since it needs to be precisely aligned.
• Side brush: You need a screwdriver to remove the side brush. You should clean it by removing tangled hairs once or twice a month, depending on whether or not you have pets.
• Wheel: You can pull the wheel out of its cavity and push it out of the socket to clear any tangled hair or stuck-on debris. You should clean it every two weeks.

Any part that's washed in water needs to be left to dry for 24 hours before being used again.

The iRobot Roomba S9 has quite a few sources of recurring costs that can add up over time.

• HEPA filter: You need to replace the HEPA filter every two months.
• Rubber brushrolls: You should replace the rubber multi-surface brushrolls every 12 months.
• Side brush: You can remove and replace the side brush every three months.
• Rear caster wheel: You should remove and replace the wheel every 12 months.

If you don't want to buy these parts individually, the manufacturer sells a 'Replenishment Kit' that includes three side brushes, multi-floor rubber brushrolls, and three HEPA filters. Look at the Roborock S7 if you're looking for a premium robot vacuum with fewer recurring costs.

This vacuum is quite easy to stow away. It's quite small for a premium robot vacuum, having a noticeably more compact footprint than alternatives like the Roborock S8 Pro Ultra. The standard charging dock is quite compact as well. Going for the S9+ variant instead gets you a self-emptying station that has a similar design to older '+' models in iRobot's lineup, like the iRobot Roomba i7+. This self-empty dock is narrow but somewhat tall.

This robot vacuum has a relatively high-capacity dustbin. At approximately half a liter in size, it's roughly twice the size of some other alternatives on the market. If you use this vacuum to deal with smaller messes, you won't likely have to empty its dustbin at the end of every cleaning session. If you buy the S9+ model, with its included self-empty station, this means far fewer frequent returns to its dock.

The standard iRobot S9 doesn't have a self-empty station; it's only bundled with a charging dock. For that kind of functionality, you'll have to buy the pricier S9+ model. The S9+'s dock is of the same design found on other iRobot models from the same era: it uses 2.4L dirtbags, advertised as sufficiently large to hold 60 days' worth of cleaning sessions. However, your real-world experience will likely vary.

• iRobot Roomba S9 robot vacuum
• Charging dock
• Charging cable
• 2x HEPA filter
• 2x multi-surface rubber brushrolls with bearings
• 2x side brush (one already inside the vacuum)
• Dirt compartment
• User guide

The iRobot Roomba S9 has remarkable battery performance. It automatically adjusts to different surface types, though you can manually adjust its power setting through three levels: 'Lower,' 'Balanced,' which is the default, and 'Exceptional.' Even in its strongest suction mode, it supplies just under 50 minutes of continuous runtime. Used more conservatively, its continuous battery life extends to over two and a half hours, which is fantastic. The LED light on top of its body notifies you of the current charge status, with the light going from white to red when its battery level is low.

This robot vacuum has a couple of different quality-of-life features. It features a dirt sensor to detect high concentrations of debris and focus its power in those areas. It also has three power levels: the high-power 'Custom + Exceptional Cleaning Power,' the default 'Detailed Clean' mode, and the energy-efficient 'Quiet Clean' mode. It also has an auto-adjusting vacuum head that can change height to suit different floor types.

This vacuum is amazingly effective on hard floors. While its side brush can fling around a lot of lightweight debris, the S9's relatively potent motor lets it pick up most of this mess. Its D-shaped body also makes it better at dealing with debris on corners compared to traditional robot vacuums with circular bodies, though a small amount of debris in these areas might still be left behind.

This vacuum does a great job on high-pile carpet. It might leave behind some finer debris like sand that's been pressed deep into corners, especially along walls and corners, but certainly to a lesser extent than robot vacuums with circular bodies that can't get as close to walls. The S9's powerful motor enables it to lift away larger debris pretty easily.

Performance on low-pile carpet is good. On this surface type, the vacuum's five-armed side brush makes quite a bit of a mess and flings around larger debris, though thankfully it does a thorough job in cleaning up that self-generated mess. It's quite effective in dealing with finer material on this surface type, though another pass might be necessary to get every last bit.

This vacuum does a good job of cleaning pet hair on low-pile carpet. Most hair is cleared within a single cleaning cycle, but you'll want to run it again to deal with strands that have been worked especially deep into carpet fibers.

The iRobot Roomba S9's real-world suction power is relatively strong for a robot vacuum, exceeding that of the iRobot Roomba i3. It isn't as potent as newer flagships like the Roborock S7 MaxV. In any case, its suction inlet is positioned too high above the contact surface to generate a tight seal on bare surfaces, resulting in low suction power measurements.

This vacuum is very powerful for a robot model. It slightly outdoes premium alternatives like the Roborock S8 in this respect and won't have much trouble lifting away heavier material.

The iRobot Roomba S9 is impressively quiet. The sound of it running won't be especially disruptive if you have it running in an adjacent room with the door closed, but you'll have to raise your voice somewhat when speaking to somebody in the same room as the vacuum while it's operating.

This robot vacuum has amazing maneuverability. Like the iRobot Roomba i7, it uses the iAdapt 3.0 navigation system to create an efficient cleaning route and maneuver around obstructions. It also goes over spots that it deems in need of additional cleaning. The vacuum isn't very tall, so it won't get stuck under tables or couches. While it can get stuck on rug tassels, it doesn't get tangled on obstructions like power cables, though it may push them around. However, unlike newer robot vacuums like the Roborock S8+/S8, it doesn't offer real-time hazard avoidance capability, which would allow it to spot and react to objects placed in its way.

The iRobot Roomba S9 is effective at sealing in fine allergens. It has an onboard HEPA filter and does a significantly better job of sealing in particles compared to other robot vacuums like the Roborock S7.

The iRobot Roomba S9 struggles with cleaning debris in cracks and crevices. It can't generate a tight enough seal against the contact surface to draw out debris in deeper cracks and crevices, and its side brush tends to scatter debris around instead of directing it towards its brushrolls. Running it in its 'Exceptional Cleaning Power' mode does help it clear a little more debris in deep and medium-depth cracks, but not by much.

The iRobot Roomba S9 does a terrible job of dealing with stains. Unlike other high-end models like the Roborock S7 MaxV, it doesn't have a mopping attachment that would allow it to scrub away dried-on stains.

This vacuum has no mopping feature.

The iRobot Roomba S9's automation features are passable. During setup with the iRobot Home companion app, it uses its navigation system to create a virtual map of the layout of your home. One convenience is that if the vacuum runs out of battery while cleaning a room, it will remember the incomplete job and return once it's been recharged. That being said, unlike newer robot vacuums like the eufy X10 Pro Omni, it lacks a front-facing camera that would allow it to spot, identify, and avoid obstacles if necessary.

You can purchase a charging station/dirt bin separately or as part of a more expensive S9 variant called the S9 Plus, which gives the vacuum a standalone dirt compartment built into its charging dock to automatically empty itself of debris and continue cleaning.

The iRobot HOME companion app is great. It allows you to schedule cleaning times for individual rooms and set up virtual boundary markers. The app also shows your previous cleaning history and remaining battery life. It's also fully compatible with Amazon Alexa and Google Home devices, so you can make specific inputs with voice commands.