The Best NU Aqua Reverse Osmosis Systems in 2026: 2 Picks
As an Amazon Associate we earn from qualifying purchases. Links on this page are affiliate links.
You need the best NU Aqua reverse osmosis systems for clean, high-flow water under your sink. This guide covers 2 models, ranked strictly by their published specifications. NU Aqua offers compact, under-sink units in white, including standard 5-stage tanks and tankless alkaline designs with UV filtration. The top pick is the NU Aqua 5-Stage Under Sink RO System, which leads for high flow under-sink filtration. Its 100 GPD capacity and lead-free faucet suit households prioritizing daily volume. We compared these picks based only on the data provided in their listings.
Quick picks
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | NU Aqua 5-Stage Under Sink RO System Best overall | high flow under-sink filtration | Check price of NU Aqua 5-Stage Under Sink RO System on Amazon |
| 2 | NU Aqua 600 GPD Tankless RO Best budget | Space-constrained kitchens needing high output | Check price of NU Aqua 600 GPD Tankless RO on Amazon |
Our 2 picks
NU Aqua 5-Stage Under Sink RO System
Best for: high flow under-sink filtration
- Filtration Stages
- 5
- Capacity (GPD)
- 100
- Design
- Under sink
- Filtration Type
- Reverse osmosis
- Installation Type
- Under sink
- Capacity
- 100 GPD
View on Amazon: NU Aqua 5-Stage Under Sink RO System Affiliate link
This NU Aqua 5-stage reverse osmosis system delivers 100 gallons per day of filtered water. It uses a HydraCoil membrane to remove over 99% of total dissolved solids. The unit includes a lead-free stainless steel faucet and quick-connect fittings for easy under-sink installation. You get a bonus PPM meter to test water quality. It is a solid choice for households needing high daily output and reliable filtration without a storage tank.
Pros
- 100 GPD high flow rate doubles standard output
- HydraCoil membrane removes 99% of 1000+ TDS
- NSF 100% lead-free stainless steel faucet included
- Bonus PPM meter for water quality testing
- Quick-connect fittings allow installation in under an hour
Cons
- Requires a 17.5-inch vertical clearance under the sink
- Heavier build at 20 pounds compared to lighter models
- No built-in storage tank to buffer flow during peak use
Good fit if
- You need a high daily water output for cooking and drinking
- You want a lead-free faucet with a premium stainless steel finish
- You prefer quick-connect fittings for straightforward under-sink installation
Skip if
- You have limited vertical space under your sink
- You require a tankless design for compact storage
- You want UV purification or alkaline remineralization stages
Verdict: NU Aqua 100 GPD 5-Stage Under Sink RO fits households that prioritize high daily flow and a lead-free faucet. It suits buyers who need reliable TDS reduction and easy installation without the bulk of a storage tank.
NU Aqua 600 GPD Tankless RO
Best for: Space-constrained kitchens needing high output
- Filtration Stages
- 5
- Capacity (GPD)
- 600 GPD
- Design
- Tankless, under sink
- Pure to Drain Ratio
- 2:1
- Filtration Type
- Reverse osmosis, alkaline, UV
- Contaminants Removed
- Sediment, rust, chlorine, VOCs, PFAS
View on Amazon: NU Aqua 600 GPD Tankless RO Affiliate link
This NU Aqua unit is a tankless reverse osmosis system with a 600 GPD capacity. It uses a 5-stage filtration process that includes an alkaline filter for remineralization and a UV-C stage for added protection. The slim design saves under-sink space, and the 2:1 pure-to-drain ratio improves efficiency. The included faucet features a color-changing LED to signal filter changes. It suits you if you want high output without a storage tank.
Pros
- 600 GPD tankless capacity for direct water flow
- 5-stage filtration includes alkaline remineralization
- UV-C filter adds extra protection layer
- Slim 5.5-inch width saves cabinet space
- 2:1 pure-to-drain water efficiency ratio
Cons
- Heavier at 25 pounds than standard tank models
- Requires electrical outlet for UV-C light
- No built-in storage tank for peak demand
Good fit if
- You need high daily water output without a tank
- You want remineralized water with added alkalinity
- You have limited under-sink vertical space
Skip if
- You prefer a system that works without electricity
- You need a large buffer tank for high volume
- You want a simpler 3-stage filtration setup
Verdict: NU Aqua 600 GPD Tankless RO System delivers high-capacity filtered water without taking up cabinet space. It fits you if you prioritize space savings and want alkaline, UV-protected water directly from the tap.
Specifications side by side
| Spec | NU Aqua 5-Stage Under Sink RO System | NU Aqua 600 GPD Tankless RO |
|---|---|---|
| Filtration Stages | 5 | 5 |
| Capacity (GPD) | 100 | 600 GPD |
| Design | Under sink | Tankless, under sink |
| Pure to Drain Ratio | not stated | 2:1 |
| Filtration Type | Reverse osmosis | Reverse osmosis, alkaline, UV |
| Contaminants Removed | not stated | Sediment, rust, chlorine, VOCs, PFAS |
| Installation Type | Under sink | Under sink |
| Features | not stated | LED smart faucet, remineralization |
| Capacity | 100 GPD | 600 GPD |
| Use | Drinking Water, Home, Kitchen | not stated |
| Color | White | White |
| Dimensions | 15 × 5.5 × 17.5 inches | 15.5 × 5.5 × 13.5 inches |
| Weight | 20 pounds | 25 pounds |
| Size | RO - Stage 5 | 5 Stage UV + Alkaline Tankless RO |
| Model | WU-100GPD-NP | KF-600GPD-UV-ALK-2FTL |
NU Aqua RO Systems Compared
NU Aqua offers two distinct under-sink RO systems. The NU Aqua 5-Stage Under Sink RO System provides 100 GPD capacity in a compact 20-pound unit. It suits households needing high daily flow without a storage tank. Its dimensions fit standard cabinets easily.
The NU Aqua 600 GPD Tankless RO System delivers significantly higher output. It weighs 25 pounds and includes alkaline and UV filtration stages. This model fits space-constrained kitchens requiring direct tap access to treated water. Both units operate as white, 5-stage systems installed under the sink.
Where NU Aqua fits
NU Aqua’s range spans from 100 GPD to 600 GPD output. The smaller 5-Stage model weighs 20 pounds and measures 17.5 inches high. The larger tankless unit weighs 25 pounds and stands 13.5 inches tall. Both units are white and designed for under-sink installation. You get standard 5-stage filtration in the base model. The premium option adds alkaline and UV features. Neither system includes a storage tank. If you need a high-capacity, space-saving solution with advanced treatment stages, this brand covers that need. Smaller capacity options or countertop designs are not available in this lineup.
How to Choose the Right NU Aqua RO System
-
Check Daily Water Output
You should match the gallons per day rating to your household size. The NU Aqua 5-Stage Under Sink RO System offers 100 GPD capacity. This output suits smaller families or those with moderate usage needs. If you require higher volume for cooking or entertaining, consider the NU Aqua 600 GPD Tankless RO. Its 600 GPD rating ensures you never run dry during peak times. Always verify the rated capacity aligns with your daily water consumption habits to avoid frustration.
-
Evaluate Installation Space
Measure your under-sink cabinet before purchasing. The NU Aqua 5-Stage Under Sink RO System measures 17.5 inches in height. This vertical profile fits standard cabinets well. The NU Aqua 600 GPD Tankless RO is slightly shorter at 13.5 inches high. Both units share a similar width of 5.5 inches. Ensure your plumbing layout accommodates the required length and width. Proper spacing allows for easy filter replacement and maintenance access without moving other items.
-
Decide on Tankless Design
Tankless systems save cabinet space by eliminating storage tanks. The NU Aqua 600 GPD Tankless RO System uses this design. It delivers water on demand directly from the tap. This suits buyers who prioritize space savings and want alkaline, UV-protected water. Standard systems like the 5-Stage model may include tanks for storage. Choose tankless if you want fresh water without waiting for tank refills. It also reduces the risk of stagnant water sitting in a reservoir for long periods.
-
Review Filtration Stages
Both listed models utilize 5-stage filtration processes. This configuration typically includes sediment, carbon, and reverse osmosis membranes. The NU Aqua 600 GPD Tankless RO adds specific features like an alkaline filter and UV filtration. These extras target pH balance and microbial safety. The standard 5-Stage Under Sink RO System focuses on core TDS reduction. Consider which additional treatments matter most for your local water quality. More stages often mean broader contaminant removal capabilities.
-
Consider Faucet Compatibility
Ensure your kitchen faucet hole can accommodate the included hardware. The NU Aqua 5-Stage Under Sink RO System is noted for its lead-free faucet option. This addresses health concerns regarding heavy metals in drinking water. The tankless model also includes a dedicated faucet for filtered water. Verify that your sink has a spare hole or that you are willing to drill one. Proper faucet installation ensures a secure connection and prevents leaks under the sink.
Frequently asked questions
Which NU Aqua RO system is best for high daily flow?
The NU Aqua 5-Stage Under Sink RO System is the top pick for high flow. It delivers 100 gallons per day. This capacity suits households that need reliable water output. The unit weighs 20 pounds and measures 17.5 inches in height. It fits standard under-sink spaces.
Does NU Aqua offer a tankless reverse osmosis option?
Yes, the NU Aqua 600 GPD Tankless RO System is available. It removes the need for a storage tank. This design saves cabinet space for you. The unit weighs 25 pounds and stands 13.5 inches tall. It provides high output directly from the tap.
What filtration stages do these NU Aqua systems use?
Both models use a 5-stage filtration process. The 5-Stage Under Sink RO handles standard purification. The Tankless version adds an alkaline filter and UV filtration. These stages target specific contaminants while improving taste. The alkaline stage helps balance pH levels.
How big is the NU Aqua 600 GPD unit?
The NU Aqua 600 GPD Tankless RO is compact. It measures 15.5 inches in length and 5.5 inches in width. The height is 13.5 inches. The total weight is 25 pounds. Its small footprint makes it ideal for tight kitchen cabinets.
Is the NU Aqua faucet lead-free?
The NU Aqua 5-Stage Under Sink RO includes a lead-free faucet. This feature ensures safe drinking water for your family. The system focuses on reducing total dissolved solids. You get clean water without worrying about lead exposure from the fixture.
What is the main difference between the two NU Aqua models?
The primary difference is capacity and design. The 5-Stage model offers 100 GPD and weighs 20 pounds. The Tankless model provides 600 GPD and weighs 25 pounds. The Tankless version also includes UV and alkaline filtration. Choose based on your space and daily water needs.