
Express Water RO5DX
Score: 88/100
iSpring RCC7AK Black
Score: 85/100Rankings

The Express Water RO5DX is a compact 5-stage under-sink reverse osmosis system featuring NSF/ANSI 58 certification and alkaline remineralization for improved taste. It offers a 50 GPD production rate and includes a leak detection shutoff for added safety. While it lacks the high capacity of larger systems, its pre-assembled design and remineralization feature make it a strong contender for standard households.

The iSpring RCC7AK-BLK is a 6-stage under-sink reverse osmosis system certified by NSF/ANSI 58 to remove up to 99% of over 1,000 contaminants. It features an alkaline remineralization stage that restores minerals and pH balance, producing bottled-water quality taste without requiring electricity. Best suited for homeowners seeking superior drinking water quality with bottled-water taste.
| Attribute | ![]() | ![]() |
|---|---|---|
5 stages | 6 stagesbest | |
50 gallons per day | 75 gallons per daybest | |
96 percent | 97.9 percentbest | |
4 gallonsbest | — | |
1,000 countbest | 1,000 countbest | |
12 monthsbest | — | |
| ↓ lower better | 5 inchesbest | 16 inches |
| ↓ lower better | 15 inchesbest | 19 inches |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | ![]() | ![]() |
|---|---|---|
Storage(1) | ||
Storage Tank Capacity (gallons) | 4 gallons | Not specified gallons |
Maintenance(1) | ||
Filter Lifespan (months) | 12 months | Not specified months |
Design(2) | ||
System Width (inches) | 5.0 inches | 16.0 inches |
System Height (inches) | 15.0 inches | 19.0 inches |
Performance(5) | ||
Filtration Stages (stages) | 5 stages | 6 stages |
Daily Production Rate (gallons per day) | 50 gallons per day | 75 gallons per day |
TDS Reduction Rate (percent) | 96 percent | 97.9 percent |
Wastewater Ratio | Standard | Not specified |
Feed Water Pressure (PSI) | 40 PSI | 40-80 PSI |
Features(1) | ||
Faucet Type | Chrome | Black |

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.
Users generally praise the system for its reliable performance, compact size, and the peace of mind provided by NSF certification.


