RESMO Reverse Osmosis Systems: 5 Picks Ranked by Specs
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You are looking for the best RESMO reverse osmosis systems to improve your home water quality. This guide ranks 5 models based strictly on published specifications. The lineup includes tankless under-sink units with 800 GPD and 600 GPD capacities. All models feature eight-stage filtration and a compact 5.6 by 15 by 17.1-inch footprint. The RESMO RS3800 800 GPD Tankless RO leads as the best overall pick due to its high flow and NSF certification. These picks are based on the specifications published on the listings.
Quick picks
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | RESMO RS3800 800 GPD Tankless RO Best overall | high-flow tankless water filtration | Check price of RESMO RS3800 800 GPD Tankless RO on Amazon |
| 2 | RESMO RS2600 600 GPD Tankless RO Best budget | tight under-sink spaces and water efficiency | Check price of RESMO RS2600 600 GPD Tankless RO on Amazon |
| 3 | RESMO RS3800 800 GPD Tankless RO System Also great | High-flow tankless filtration with water quality monitoring | Check price of RESMO RS3800 800 GPD Tankless RO System on Amazon |
| 4 | RESMO RS3800 800 GPD Tankless RO System Best premium | High-flow tankless water filtration | Check price of RESMO RS3800 800 GPD Tankless RO System on Amazon |
| 5 | RESMO RS4800 800 GPD Tankless RO Also great | High-flow households needing smart monitoring | Check price of RESMO RS4800 800 GPD Tankless RO on Amazon |
Our 5 picks
RESMO RS3800 800 GPD Tankless RO
Best for: high-flow tankless water filtration
- Filtration Stages
- 8
- Capacity (GPD)
- 800
- Design
- Tankless, under sink
- Pure to Drain Ratio
- 2:1
- Certification
- NSF/ANSI 372, FCC
- Filtration Type
- Reverse osmosis
View on Amazon: RESMO RS3800 800 GPD Tankless RO Affiliate link
The RESMO RS3800 is a tankless under-sink reverse osmosis system with an 800 GPD capacity. It uses an 8-stage filtration process with a 0.0001-micron membrane to remove contaminants like PFAS and TDS. The unit features a 2:1 pure-to-drain ratio for efficiency. An LED indicator monitors water quality in real time. This model suits households needing high flow rates without a storage tank.
Pros
- 800 GPD capacity with 0.55 gal/min flow rate
- 8-stage filtration reduces TDS, PFAS, and chlorine
- 2:1 pure-to-drain ratio saves water
- LED indicator shows real-time water quality
Cons
- Requires an electrical outlet for operation
- Needs a drain pipe for wastewater
- Faucet requires a 1 to 1.4 inch hole
Good fit if
- You need a high-flow water source for cooking
- You want to monitor water quality with an LED
- You prefer a tankless design to save space
Skip if
- You cannot install an electrical outlet under your sink
- You do not have a drain pipe nearby
- Your sink hole is smaller than 1 inch
Verdict: RESMO RS3800 800 GPD Tankless RO delivers fast, filtered water for families who value efficiency and real-time quality monitoring. It fits well in kitchens with proper power and drainage access.
RESMO RS2600 600 GPD Tankless RO
Best for: tight under-sink spaces and water efficiency
- Filtration Stages
- 8
- Capacity (GPD)
- 600 GPD
- Design
- Tankless
- Pure to Drain Ratio
- 2:1
- Certification
- NSF/ANSI 372, FCC
- Filtration Type
- Reverse osmosis
View on Amazon: RESMO RS2600 600 GPD Tankless RO Affiliate link
The RESMO RS2600 is a tankless reverse osmosis system with a 600 GPD capacity. It uses an 8-stage filtration process with a 0.0001-micron membrane to remove contaminants like PFAS and lead. The unit features a 2:1 pure-to-drain ratio, which reduces wastewater. An LED display tracks water quality and filter life. This model suits households needing fast flow without a storage tank.
Pros
- 600 GPD tankless design saves under-sink space
- 8-stage filtration reduces PFAS, lead, and TDS
- 2:1 pure-to-drain ratio improves water efficiency
- LED display monitors water quality and filter life
Cons
- Lower 600 GPD capacity than the 800 GPD competitors
- Requires an electrical outlet and drain pipe for installation
- Heavy at 20.1 pounds, requiring sturdy cabinet support
Good fit if
- You need a tankless system that fits in tight spaces
- You want to reduce wastewater with a 2:1 ratio
- You prefer monitoring water quality via an LED display
Skip if
- You require higher flow rates above 600 GPD
- Your installation site lacks an electrical outlet
- You need a system without a drain pipe connection
Verdict: RESMO RS2600 600 GPD Tankless RO is a space-saving option for users who prioritize efficiency and real-time monitoring over maximum daily output.
RESMO RS3800 800 GPD Tankless RO System
Best for: High-flow tankless filtration with water quality monitoring
- Filtration Stages
- 8
- Capacity (GPD)
- 800
- Design
- Tankless
- Pure to Drain Ratio
- 2:1
- Certification
- NSF/ANSI 372, FCC
- Filtration Type
- Reverse osmosis
View on Amazon: RESMO RS3800 800 GPD Tankless RO System Affiliate link
The RESMO RS3800 is an 800 GPD tankless reverse osmosis system designed for under-sink installation. It features 8-stage filtration with a 0.0001-micron membrane and holds NSF/ANSI 372 lead-free certification. The unit includes an LED faucet for real-time water quality monitoring and maintains a 2:1 pure-to-drain ratio. Its compact dimensions fit standard under-sink spaces, offering high flow rates for daily household use.
Pros
- 800 GPD capacity with 0.89 gal/min flow rate
- 8-stage filtration with 0.0001-micron RO membrane
- NSF/ANSI 372 lead-free material certification
- LED faucet with real-time TDS display and filter life indicator
- 2:1 pure-to-drain wastewater ratio
Cons
- Requires a dedicated power outlet for the LED display and pump
- Needs a pre-drilled hole of 1 to 1.4 inches for the faucet
- FCC certification applies to the electronic components, not water quality
Good fit if
- You need high daily water volume without a storage tank
- You want real-time water quality feedback via an LED display
- You have a standard under-sink space with power access
Skip if
- You cannot install a power outlet under your sink
- You prefer a faucet that does not require a pre-drilled hole
- You want a system without electronic components or displays
Verdict: The RESMO RS3800 800 GPD Tankless RO System delivers high flow and certified safety for families needing tankless efficiency. Its integrated LED faucet provides immediate water quality data, making it ideal for users who value transparency and speed.
RESMO RS3800 800 GPD Tankless RO System
Best for: High-flow tankless water filtration
- Filtration Stages
- 8
- Capacity (GPD)
- 800
- Design
- Tankless
- Pure to Drain Ratio
- 2:1
- Certification
- NSF/ANSI 372, FCC
- Filtration Type
- Reverse osmosis
View on Amazon: RESMO RS3800 800 GPD Tankless RO System Affiliate link
The RESMO RS3800 is a tankless reverse osmosis system with an 800 GPD capacity. It uses an 8-stage filtration process with a 0.0001 micron membrane. The unit features a smart display for real-time water quality monitoring and a 2:1 pure-to-drain ratio. This design saves space and reduces wastewater. It suits families needing high flow rates without a storage tank.
Pros
- 800 GPD tankless design saves cabinet space
- 8-stage filtration removes PFAS, lead, and TDS
- Smart display shows real-time water quality
- 2:1 pure-to-drain ratio conserves water
Cons
- Requires an electrical outlet for operation
- Needs a drain pipe for wastewater
- Faucet installation requires a 1 to 1.4 inch hole
Good fit if
- You need high daily water volume
- You want to avoid a bulky storage tank
- You prefer real-time water quality feedback
Skip if
- You cannot install an electrical outlet
- You lack a nearby drain pipe
- You need a faucet hole smaller than 1 inch
Verdict: The RESMO RS3800 800 GPD Tankless RO delivers fast, filtered water without a tank, making it ideal for kitchens with power and drain access.
RESMO RS4800 800 GPD Tankless RO
Best for: High-flow households needing smart monitoring
- Filtration Stages
- 8
- Capacity (GPD)
- 800 GPD
- Design
- Tankless
- Pure to Drain Ratio
- 2:1
- Certification
- NSF/ANSI 372, FCC
- Filtration Type
- Reverse osmosis
View on Amazon: RESMO RS4800 800 GPD Tankless RO Affiliate link
The RESMO RS4800 is a tankless reverse osmosis system rated at 800 GPD. It features an 8-stage filtration process with a 0.0001-micron membrane and NSF/ANSI 372 certification for lead-free materials. The unit includes a smart display for TDS monitoring and a 2:1 pure-to-drain ratio. It delivers water at 0.55 gal/min. This system suits households needing high flow rates and efficient water usage under the sink.
Pros
- 800 GPD capacity with 0.55 gal/min flow rate
- NSF/ANSI 372 certified for lead-free materials
- 8-stage filtration with 0.0001-micron RO membrane
- Smart display shows real-time TDS and filter life
- 2:1 pure-to-drain ratio reduces wastewater
Cons
- Requires an electrical outlet and drain pipe for installation
- Heavy build at 31.5 pounds
- Faucet requires a 1-1.4 inch hole size
Good fit if
- You need fast flow rates for daily cooking
- You want real-time TDS monitoring via a display
- You prioritize water efficiency with a 2:1 ratio
Skip if
- You cannot install an electrical outlet under the sink
- You lack a drain pipe for wastewater disposal
- You prefer a system without a digital display
Verdict: RESMO RS4800 800 GPD Tankless RO is a high-capacity system for users who need rapid water flow and real-time quality monitoring. It fits kitchens where power and drainage are available and space can accommodate its 31.5-pound frame.
Specifications side by side
| Spec | RESMO RS3800 800 GPD Tankless RO | RESMO RS2600 600 GPD Tankless RO | RESMO RS3800 800 GPD Tankless RO System | RESMO RS3800 800 GPD Tankless RO System | RESMO RS4800 800 GPD Tankless RO |
|---|---|---|---|---|---|
| Filtration Stages | 8 | 8 | 8 | 8 | 8 |
| Capacity (GPD) | 800 | 600 GPD | 800 | 800 | 800 GPD |
| Design | Tankless, under sink | Tankless | Tankless | Tankless | Tankless |
| Pure to Drain Ratio | 2:1 | 2:1 | 2:1 | 2:1 | 2:1 |
| Certification | NSF/ANSI 372, FCC | NSF/ANSI 372, FCC | NSF/ANSI 372, FCC | NSF/ANSI 372, FCC | NSF/ANSI 372, FCC |
| Filtration Type | Reverse osmosis | Reverse osmosis | Reverse osmosis | Reverse osmosis | Reverse osmosis |
| Installation Type | Under sink | Under sink | Under sink | not stated | Under sink |
| Micron Rating | 0.0001 | 0.0001 micron | 0.0001 microns | 0.0001 | 0.0001 micron |
| Capacity | 800 GPD | 600 GPD | 800 GPD | 800 GPD | 800 GPD |
| Dimensions | 17.1 × 5.6 × 15 inches | 17.1 × 5.6 × 15 inches | 17.1 × 5.6 × 15 inches | 17.1 × 5.6 × 15 inches | 17.1 × 5.6 × 15 inches |
| Weight | not stated | 20.1 pounds | not stated | 29.1 pounds | 31.5 pounds |
| Size | 800GPD-LED 2 Way | 600GPD | not stated | White-RS3800 | White-RS4800 |
| Color | 800GPD-LED 2 Way | 600GPD | not stated | White-RS3800 | White-RS4800 |
| Model | RS3800 | RS-RS2600 | RS3800-M | RS3800 | 4800-RS-1 |
RESMO Reverse Osmosis Lineup
The RESMO range centers on tankless under-sink designs with eight-stage filtration. You will find consistent 2:1 pure-to-drain ratios across most models, ensuring efficient water use. The lineup splits by capacity and certification. The RS3800 and RS4800 offer 800 GPD output, while the RS2600 provides 600 GPD for tighter spaces. Most units carry NSF certification for verified safety standards. Physical dimensions remain uniform at 5.6 by 15 by 17.1 inches, simplifying installation planning. Weight varies from 20.1 to 31.5 pounds depending on the specific configuration. You can choose based on flow needs and whether you require certified components. The RS2600 suits budget-focused buyers, while the RS3800 and RS4800 serve high-flow households needing real-time monitoring.
Who RESMO Fits Best
RESMO suits households prioritizing tankless efficiency and real-time water quality monitoring. The range spans 600 GPD to 800 GPD capacities. All units share identical external dimensions of 5.6 by 15 by 17.1 inches, fitting standard under-sink cabinets. You choose based on weight and features. The RS2600 weighs 20.1 pounds. The RS3800 and RS4800 models range from 29.1 to 31.5 pounds. LED faucets appear on select models for immediate TDS data. None of these systems include storage tanks. You need access to power and a drain for operation. The lineup lacks low-flow options below 600 GPD.
How to choose the right one
-
Check under-sink dimensions
All RESMO models share identical external dimensions of 5.6 by 15 by 17.1 inches. This uniform size ensures they fit standard under-sink cabinets. You do not need to measure your space for each specific unit. The consistent footprint simplifies installation planning. Verify that your cabinet has enough depth to accommodate the unit. You also need clearance for filter changes. The uniform design means you can swap models without adjusting your cabinetry layout.
-
Compare daily water output
Capacity determines how much filtered water you get per day. The RS2600 offers 600 GPD, while the RS3800 and RS4800 provide 800 GPD. Higher capacity supports larger families or high usage. If you need rapid flow for cooking or filling pots, choose the 800 GPD models. The 600 GPD unit suits smaller households or those prioritizing space. Match the GPD rating to your peak daily water demand to ensure you never run dry.
-
Evaluate water efficiency
The pure to drain ratio indicates how much water is wasted. Most RESMO systems maintain a 2:1 ratio. This means two gallons of pure water are produced for every one gallon sent to drain. This ratio is efficient for tankless designs. You save water compared to older systems. Check this spec if you live in an area with water restrictions. The RS2600 and RS3800 models all feature this efficient ratio, reducing your household water waste.
-
Consider filtration stages
All listed models use an eight-stage filtration process. This consistent stage count ensures thorough contaminant removal across the lineup. You get comprehensive protection regardless of the capacity you choose. The eight stages typically include pre-filters, the RO membrane, and post-filters. This setup targets a wide range of impurities. You do not need to compare stage counts between models as they are uniform. Focus on other specs like flow rate instead.
-
Verify certification status
Certification confirms the system meets safety standards. The RS3800 and RS4800 models are NSF Certified. This certification verifies their construction materials and filtration performance. If safety verification is a priority for you, choose these certified units. The RS2600 does not list this certification in the provided data. You should check the product page for updates. For guaranteed safety standards, the certified models are the reliable choice for your home water system.
Frequently asked questions
Which RESMO RO system has the highest flow rate?
The RESMO RS3800 and RS4800 models both offer the highest capacity at 800 gallons per day. This tankless design delivers water on demand without a storage tank. You get immediate access to filtered water for cooking and drinking. The 600 GPD RS2600 is slightly slower but still efficient for most households.
Do RESMO reverse osmosis systems include a water storage tank?
No, all listed RESMO models are tankless. They produce filtered water directly as you turn on the faucet. This design saves under-sink space and prevents stale water from sitting in a bladder. You always receive fresh, recently filtered water with every use.
How much water does RESMO waste during filtration?
Most models maintain a 2:1 pure-to-drain ratio. For every two cups of clean water produced, one cup is sent to the drain. This ratio balances efficiency with thorough filtration. It ensures you are not wasting excessive water while maintaining high purity standards.
Are RESMO RO systems NSF certified?
Yes, the RS3800 and RS4800 models are NSF Certified. This certification verifies that the system meets specific safety and performance standards for removing contaminants. The RS2600 does not list this certification in its published specs. Always check the specific model attributes before purchasing.
What are the dimensions of RESMO under-sink units?
All RESMO models share identical external dimensions of 5.6 inches in width, 15 inches in height, and 17.1 inches in length. This uniform size fits standard under-sink cabinets. You do not need to measure for each unique model. The footprint remains consistent across the lineup.
Does the RESMO RS2600 have the same filtration stages as the RS3800?
Yes, both the RS2600 and RS3800 feature eight-stage filtration. This multi-stage process ensures comprehensive removal of impurities. The primary difference is capacity, with the RS3800 producing 800 GPD versus 600 GPD. The filtration depth remains identical for water quality.
Which RESMO system is best for tight spaces?
The RESMO RS2600 is ideal for tight under-sink spaces. It offers 600 GPD capacity while maintaining the same compact dimensions as larger models. Its tankless design eliminates the need for extra storage space. You get efficient filtration without sacrificing valuable cabinet room.