8 Best Reverse Osmosis Systems for Apartments (October 2026)
The best reverse osmosis systems for apartments include the Waterdrop G3P600 for a compact cabinet, the Waterdrop G5P500A for alkaline water options, and the Waterdrop G2P600 for higher stated capacity.
On this page (6 sections)
- How we chose apartment reverse osmosis systems
- The best reverse osmosis systems for apartments and rentals
- What should renters check before installing an RO system?
- Is a tankless system a good fit for a small apartment kitchen?
- How should you compare water use and capacity?
- Which apartment reverse osmosis system should you choose?
The best reverse osmosis system for an apartment is usually a tankless model that fits the cabinet and the lease. Our top pick, Waterdrop G3P600, adds a smart display faucet and a 2:1 pure-to-drain ratio, but it needs under-sink electricity and drilled connections.
Apartment kitchens often have less cabinet room than a house kitchen, and rental rules can limit changes to the sink. Measure the available space, locate an outlet, and check whether you can add a faucet hole before choosing a system.
For a wider look at compact models, see our guide to the best tankless reverse osmosis systems. If a storage tank is acceptable, compare under-sink reverse osmosis systems with a tank.
Our picks at a glance
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How we chose apartment reverse osmosis systems
The best apartment reverse osmosis systems balance cabinet fit, installation needs and water use. We compared dimensions, power requirements, stated capacity, drainage ratios and features that affect everyday use.
Our score weighs specs, features and buyer feedback against what you're shopping for. Apartment fit depends on your actual sink cabinet and lease, so confirm those details before buying.
| Product | Best for | Design | Dimensions | Power | Our score |
|---|---|---|---|---|---|
| Waterdrop G3P600 | a compact cabinet | Tankless | 18.12 x 5.67 x 17.72 in | Corded electric | 8.8 |
| Waterdrop G5P500A | alkaline water options | Tankless | 16.69 x 5.69 x 13.9 in | Corded electric | 8.6 |
| Waterdrop G2P600 | higher stated capacity | Tankless | 17.3 x 5.9 x 14 in | 8.2 | |
| Waterdrop WD-T4-A | two water streams | Tankless | 16.54 x 6.22 x 17.95 in | 7.8 | |
| Waterdrop G2 | a smaller tankless setup | Tankless | 17.3 x 5.9 x 14 in | 7.7 | |
| Waterdrop T3-M | mineralized water | Tankless | 13.39 x 6.22 x 17.95 in | 7.4 | |
| Waterdrop T3-C | wall mounting | Tankless; under-sink or wall-mounted | 13.39 x 6.22 x 17.95 in | 7.3 | |
| Glacier Fresh GFU03 | kitchens without an outlet | Water-powered, no external tank | 13.58 x 8.27 x 16.54 in | No electric drive | 7.2 |
The best reverse osmosis systems for apartments and rentals
The right system depends on whether your main constraint is cabinet space, power access, water options or rental approval. Check the product dimensions against the space available, then leave room for tubing and filter changes.
Waterdrop G3P600: Best for a compact cabinet
- Tankless design
- 18.12 x 5.67 x 17.72 in
- 600 GPD
- Smart display faucet
- 2:1 pure to drain ratio
- Requires under-sink electricity
A tankless body and smart display faucet suit a small kitchen where you want water information at the tap. Check the cabinet measurements and plan for electricity and drilled connections.
Pros
- 600 GPD capacity
- Smart faucet tracks TDS and filter life
- 2:1 pure to drain ratio
Cons
- Requires under-sink electricity
- Drilling is required for faucet and drain connections
The Waterdrop G3P600 is the best fit for an apartment kitchen where you want a compact tankless unit with clear filter information. It measures 18.12 x 5.67 x 17.72 in and has a display faucet that monitors TDS and tracks filter life.
Waterdrop gives this model a stated capacity of 600 gallons per day and a 2:1 pure-to-drain ratio. Its product information also describes NSF/ANSI 58 certification for TDS reduction, NSF/ANSI 372 certification for lead-free material and NSF 42 testing and certification for chlorine, taste and odor reduction.
The faucet and drain connection require drilling, and the system needs under-sink electricity. Measure the cabinet, including space for connections, and get approval before making holes in a rental sink.
Choose it for a rental where the owner permits installation and the cabinet has a nearby outlet. If you want to understand the drain line before choosing an RO system, read why reverse osmosis systems waste water.
Waterdrop G5P500A: Best for alkaline water options
- Tankless design
- 16.69 x 5.69 x 13.9 in
- 500 GPD
- Alkaline mineralization
- 2:1 pure to drain ratio
- Requires corded electricity
This compact tankless system adds alkaline mineralization and a 2:1 pure-to-drain ratio. Its faucet installation requires drilling, so renters should confirm permission first.
Pros
- Alkaline mineralization
- 500 GPD capacity
- Can connect to an ice maker or fridge with Waterdrop XT
Cons
- Requires electricity
- Faucet installation requires drilling
The Waterdrop G5P500A suits apartment dwellers who want mineralization as well as reverse osmosis. Its tankless body measures 16.69 x 5.69 x 13.9 in, and the system adds minerals including calcium, magnesium, sodium and potassium.
Waterdrop states a 500 GPD capacity and a 2:1 purified-water ratio. It can also connect to an ice maker or refrigerator through Waterdrop XT, which may be useful when the kitchen setup supports that connection.
The system needs corded electricity, and faucet installation requires a drilled countertop hole. Ask permission before installation and check whether the kitchen has the required space and connections.
Pick this model if alkaline mineralization is a priority in a rental where installation is allowed. For a closer look at how tankless options differ, see our tankless RO system guide.
Waterdrop G2P600: Best for higher stated capacity
- Tankless design
- 17.3 x 5.9 x 14 in
- 600 GPD
- 2:1 pure to drain ratio
- NSF/ANSI 372 certified for lead-free materials
The G2P600 combines a 600 GPD capacity with a 2:1 pure-to-drain ratio. Its tankless body saves cabinet space, though you still need to check faucet and plumbing changes with your landlord.
Pros
- 600 GPD capacity
- 2:1 pure to drain ratio
- Twist-and-pull filter design
Cons
- Faucet installation requires a countertop hole
- Dimensions do not include room for connections
The Waterdrop G2P600 is a reasonable choice when stated capacity matters and you want to avoid a separate tank. It measures 17.3 x 5.9 x 14 in, produces up to 600 GPD, and uses a 2:1 pure-to-drain ratio.
Waterdrop says the system is certified to NSF/ANSI 372 for lead-free materials. Its twist-and-pull filters are designed for replacement without moving the system, a useful detail when the unit sits in a tight cabinet.
The system is corded electric and comes with a faucet, so check the outlet and installation needs. Its dimensions describe the unit itself, not extra room for pipes or filter access.
Choose it if the cabinet fits and you want the higher stated capacity among these compact picks. If you're comparing tank and tankless layouts, our guide to tank vs tankless reverse osmosis explains the space trade-off.
Waterdrop WD-T4-A: Best for two water streams
- Tankless design
- 16.54 x 6.22 x 17.95 in
- 450 GPD
- Standard RO and mineral-enhanced alkaline streams
- Requires electricity
The WD-T4-A offers a standard RO stream and a separate mineral-enhanced alkaline stream. Choose it if that flexibility matters and you can make room for its taller cabinet body.
Pros
- Two purified water options
- 450 GPD capacity
- Filter reminders use lights and buzzer alerts
Cons
- Requires an electrical connection
- Faucet installation requires drilling
The Waterdrop WD-T4-A makes sense if you want a choice between a standard RO stream and a mineral-enhanced alkaline stream. Its body measures 16.54 x 6.22 x 17.95 in, so its height deserves a close check under a low sink or around existing shelves.
The system has a stated capacity of 450 GPD and a 2:1 pure-to-drain ratio. Its filter reminders use indicator lights and buzzer alerts, and Waterdrop gives separate replacement intervals for its filters and mineralizer.
It requires an electrical connection, and the faucet needs a drilled countertop hole. For a rental, confirm both the outlet and permission for installation before making a decision.
Pick it when two water streams matter more than a lower profile. Buyers focused on straightforward mineralized RO can also compare the Waterdrop G5P500A.
Waterdrop G2: Best for a smaller tankless setup
- Tankless design
- 17.3 x 5.9 x 14 in
- 400 GPD
- 1:1 pure to drain ratio
- Requires under-sink electricity
The G2 has a lower stated capacity than the G2P600 and uses a 1:1 pure-to-drain ratio. Its tankless design can suit a small kitchen if the outlet and drilled connections are workable.
Pros
- Tankless cabinet
- 1:1 pure to drain ratio
- Twist-and-pull filter replacement
Cons
- Requires under-sink electricity
- Installation requires drilling holes
The Waterdrop G2 is a compact tankless option with a lower stated capacity than the G2P600. It measures 17.3 x 5.9 x 14 in, offers 400 GPD and has a 1:1 pure-to-drain ratio.
This corded system needs an outlet under the sink. Installation also requires drilled holes, so the tankless design saves cabinet room but does not make the setup rental-friendly by itself.
Its filters use a twist-and-pull design, and the system includes a mechanical faucet. Check the cabinet for room to reach the filters, and confirm the installation details with the property manager.
Choose the G2 when its capacity and 1:1 ratio suit your household and you have permission to install it. If you're deciding whether a non-RO filter might be enough, compare under-sink water filters that skip reverse osmosis.
Waterdrop T3-M: Best for mineralized water
- Tankless design
- 13.39 x 6.22 x 17.95 in
- 450 GPD
- Mineral infusion
- 2:1 pure to drain ratio
- Requires electricity
This tankless system adds calcium, magnesium and other minerals after RO filtration. Its smaller stated length helps where cabinet width is limited, while its height still needs checking.
Pros
- Mineral infusion
- 2:1 pure to drain ratio
- Filter alerts and automatic flushing
Cons
- Requires electricity
- Faucet installation requires drilling
The Waterdrop T3-M fits a buyer who wants mineral-infused RO water and a tankless design. Its stated size is 13.39 x 6.22 x 17.95 in, with a 450 GPD capacity and 2:1 pure-to-drain ratio.
The system adds calcium, magnesium and other minerals after filtration, according to Waterdrop. Smart alerts indicate when filters need replacement, and automatic flushing is included.
It needs electricity, and faucet installation requires drilling. Its shorter body length may ease placement in some cabinets, but measure the full available area and account for the unit's height.
Pick the T3-M if mineral infusion is the feature you want and you have an outlet. If filter changes are a concern, read how often reverse osmosis filters need changing.
Waterdrop T3-C: Best for wall mounting
- Tankless design
- 13.39 x 6.22 x 17.95 in
- 450 GPD
- Under-sink or wall-mounted installation
- 2:1 pure to drain ratio
The T3-C can be installed under the sink or on a wall, which may help when cabinet storage is tight. It still needs an electrical connection and a drilled faucet hole.
Pros
- Under-sink or wall-mounted installation
- 2:1 pure to drain ratio
- Smart filter alerts and automatic flushing
Cons
- Requires electricity
- Faucet installation requires drilling
The Waterdrop T3-C stands out because it can be mounted under the sink or on a wall. It measures 13.39 x 6.22 x 17.95 in and has a stated capacity of 450 GPD.
Its 2:1 pure-to-drain ratio, smart filter alerts and automatic flushing suit someone who wants those functions in a tankless unit. Waterdrop says it can save up to 70% of under-sink space compared with traditional tank-based systems.
The T3-C requires electricity and a drilled faucet hole. Wall mounting may free up cabinet room, but check that the chosen location works for water lines and future filter access.
Choose it if wall mounting solves a specific cabinet-space problem and your rental allows the changes. For the general fit and installation checks, see our under-sink RO installation guide.
Glacier Fresh GFU03: Best for kitchens without an outlet
- Water-powered, no electricity required
- 13.58 x 8.27 x 16.54 in
- 800 GPD
- 3:1 pure to drain ratio
- Requires a drilled faucet hole
The GFU03 runs without electricity and has a built-in tank, so it avoids a separate external storage tank. Its wider body and faucet hole requirement still call for a careful rental-kitchen fit check.
Pros
- No electricity required
- 3:1 pure-to-drain ratio
- Built-in water pressure gauge
Cons
- Needs at least 40 PSI inlet pressure for the recommended flow
- Faucet installation requires drilling
The Glacier Fresh GFU03 is the only electric-free option in this group. Its water-powered design has a built-in tank, a stated capacity of 800 GPD and a 3:1 pure-to-drain ratio.
The body measures 13.58 x 8.27 x 16.54 in, making it wider than several other picks. Glacier Fresh recommends at least 40 PSI inlet pressure for its stated flow, and says lower pressure reduces flow output.
The system still needs a drilled sink hole for its faucet. Its instructions also call for flushing the cartridge under running water for 10 to 20 minutes after installation and each filter replacement.
Choose the GFU03 if you lack an outlet and can accommodate its width and installation needs. If you suspect low supply pressure, our guide to low reverse osmosis water pressure covers common causes.
What should renters check before installing an RO system?
Renters should check the lease, sink layout and utility connections before buying an under-sink reverse osmosis system. Permission matters because many models require drilled holes and changes to the drain connection.
Measure cabinet width, height and depth, then account for the system, hoses, shutoff valves and room to change filters. Confirm whether an outlet is available if your chosen unit needs electricity.
If drilling is not allowed, look for a countertop system or ask the property manager about an approved alternative. Keep any removed fittings so the sink can be restored when you move.
Is a tankless system a good fit for a small apartment kitchen?
A tankless RO system can suit a small apartment kitchen because it removes the need for a separate storage tank. It still needs enough space for its body, plumbing connections and filter access.
A compact body can be easier to place, but dimensions vary in all three directions. Compare the measurements with your cabinet and leave room to reach cartridges without moving the unit.
Tankless models in this guide also differ in power needs and drainage ratios. Check both before deciding that the smallest listed unit is automatically the best fit.
How should you compare water use and capacity?
Compare the stated pure-to-drain ratio and capacity, but treat them as model specifications rather than a guarantee of your home's output. Incoming water pressure and installation conditions can affect flow.
Among these picks, ratios range from 1:1 to 3:1, while stated daily capacities range from 400 to 800 GPD. A higher number alone doesn't show how well a system fits a small household or its cabinet.
If water use is a major concern, choose a model with a ratio that suits your priorities and check its installation requirements. The guide to RO wastewater explains what the drain line does.
Which apartment reverse osmosis system should you choose?
Choose the Waterdrop G3P600 if you want a smart faucet and a 2:1 ratio and have outlet access and permission to drill. Pick the Glacier Fresh GFU03 if avoiding electricity matters and its wider cabinet fits.
For mineralized water, compare the Waterdrop G5P500A, WD-T4-A and T3-M by their dimensions and features. If you can't drill or change plumbing, ask your property manager about approved options before choosing an under-sink system.
Our top 3 picks at a glance
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Frequently asked questions
Can you install a reverse osmosis system in an apartment?
Yes, if the kitchen has space, a suitable water connection and permission for any needed changes. Many under-sink systems require a faucet hole and a drain connection, and electric models also need an outlet.
Check your lease or ask the property manager before drilling or changing plumbing.
Is tankless reverse osmosis better for an apartment?
Tankless RO can save cabinet space because it does not use a separate storage tank. Several picks here are less than 6.3 in wide, but the system still needs room for tubing, filters and access during replacement.
Measure the full installation area before choosing by body dimensions alone.
Does an apartment reverse osmosis system need electricity?
Many tankless models need an electrical connection under the sink. The Glacier Fresh GFU03 is described as water-powered and requires no electric drive, while Waterdrop models in this guide require electricity.
Check outlet access and your chosen model's installation needs before buying.
Can I take an under-sink RO system when I move?
Often you can remove the unit, but faucet holes, drain connections and plumbing changes may remain. Ask your landlord about installation and removal, then keep the original fittings and follow the system's instructions when restoring the sink.
A countertop system may be easier to move if you cannot alter the kitchen.
