
Express Water RO5DX
Score: 85/100
Frizzlife SK99
Score: 88/100Rankings

The Frizzlife SK99 NEW is a highly rated, NSF-certified under-sink filter that offers a direct-connect installation and a high 2 GPM flow rate. It excels in contaminant removal, including PFAS and lead, while retaining beneficial minerals. The main limitations are its sensitivity to water hardness and temperature, and it does not reduce TDS. It is ideal for families seeking premium protection without renovation costs.

The Express Water RO5DX is a 5-stage reverse osmosis system that provides high-quality purified water with NSF/ANSI 58 certification and alkaline remineralization. Its main trade-off is the production of wastewater and the need for regular filter maintenance. It is best suited for households of 4+ people seeking reliable daily drinking water with improved taste.
| Attribute | ![]() | ![]() |
|---|---|---|
0.8 gallons per minute | 2 gallons per minutebest | |
12 monthsbest | 12 monthsbest | |
6best | 3 | |
50 gallons | 1,600 gallonsbest | |
1 yearsbest | — | |
| ↓ lower better | 15 inches | 14 inchesbest |
| ↓ lower better | 5 inchesbest | 5 inchesbest |
| ↓ lower better | 14 inchesbest | 15 inches |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | ![]() | ![]() |
|---|---|---|
Value & Warranty(1) | ||
Warranty (years) | 1 years | years |
Dimensions & Fit(2) | ||
Height (inches) | 15.0 inches | 14.0 inches |
Depth (inches) | 14.0 inches | 15.0 inches |
Performance & Filtration(7) | ||
Certifications | NSF/ANSI 58 | NSF/ANSI 42 & 53 |
Contaminants Removed | Lead, Chlorine, Fluoride, Arsenic, PFAS, Bacteria | Lead, Chlorine, Chloramine, Fluoride, PFAS |
Flow Rate (gallons per minute) | 0.8 gallons per minute | 2 gallons per minute |
Filtration Stages | 6 | 3 |
Filter Capacity (gallons) | 50 gallons | 1600 gallons |
Filtration Technology | Reverse Osmosis | Carbon Block |
TDS Reduction (percent) | 93-99 percent | 0 percent |
Features & Accessories(1) | ||
Included Faucet | true | false |
Installation & Compatibility(2) | ||
Installation Type | Under Sink | Direct Connect |
Operating Pressure (psi) | 40 psi | 20-80 psi |


Products in the top-left offer the best value (high score, low price).

Professional reviewers highlight the RO5DX's NSF/ANSI 58 certification as a key strength, validating its TDS reduction capabilities and material safety. While experts note that the certification does not cover the full range of 158 claimed contaminants, they consider TDS reduction the most important metric for RO systems. Hands-on testing confirmed a 93% TDS reduction rate, though some TDS creep was observed during idle periods. The pre-assembled kit is praised for simplifying installation.
Users generally praise the system for its reliable performance, compact size, and the peace of mind provided by NSF certification. The all-in-one kit format is appreciated for its convenience, and users report a noticeable improvement in water taste. Maintenance is described as simple and manageable for non-technical users.

Professional reviewers, including R3 Recommendations, rate the SK99 NEW highly at 8.5/10 overall, praising its value proposition and direct-connect innovation. Experts highlight that it delivers premium, NSF-certified filtration without the premium pricing or complex installation associated with traditional under-sink systems.
No specific consumer quotes or sentiment data were provided in the source material.
