
iSpring CU-A4
Score: 72/100
Waterdrop WD-TSA-UF
Score: 75/100Rankings

The Waterdrop WD-TSA-UF is a 9-stage under-sink water filtration system utilizing 0.01 μm ultrafiltration technology to reduce contaminants while retaining beneficial minerals. It features a compact design with three replaceable cartridges and is certified lead-free by NSF/ANSI 372. It is best suited for homeowners with municipal water supplies seeking improved taste and reduced chlorine.

The iSpring CU-A4 is a compact, tankless 4-stage ultrafiltration system that removes up to 99% of 700 contaminants while retaining beneficial minerals and producing zero wastewater. It lacks independent third-party testing data and does not reduce TDS, which are limitations for users seeking comprehensive purification. It is best suited for apartment dwellers and RV owners with limited under-sink space who prioritize mineral retention.
| Attribute | ![]() | ![]() |
|---|---|---|
0.5 gallons per minutebest | — | |
6 monthsbest | 6 monthsbest | |
4 | 9best | |
1 yearsbest | — | |
| ↓ lower better | 12.5 inches | 4.3 inchesbest |
| ↓ lower better | 4.5 inchesbest | 12.9 inches |
| ↓ lower better | 10.5 inchesbest | 16.8 inches |
0 percentbest | 0 percentbest |
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(3) | ||
Height (inches) | 12.5 inches | 4.3 inches |
Width (inches) | 4.5 inches | 12.9 inches |
Depth (inches) | 10.5 inches | 16.8 inches |
Performance & Filtration(4) | ||
Certifications | NSF/ANSI | NSF/ANSI 372 |
Contaminants Removed | Lead, Chlorine, PFAS, Arsenic, Heavy Metals, Chloramine, Hydrogen Sulfide, Rust, Sand, Dirt | Multiple |
Flow Rate (gallons per minute) | 0.5 gallons per minute | gallons per minute |
Filtration Stages | 4 | 9 |
Features & Accessories(2) | ||
Included Faucet | true | false |
Remineralization | false | true |


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

The search results consist primarily of manufacturer product pages and retailer listings, with no independent professional reviews or third-party testing data included. Consequently, there is no expert editorial assessment available to validate the system's actual performance relative to the manufacturer's claims regarding contaminant removal and durability.
The provided data does not contain user reviews, customer testimonials, or recurring feedback patterns from everyday consumers. While Home Depot lists 81 customer questions and answers, the specific content of this user feedback is not included in the research data.

Professional assessment is limited due to a lack of detailed expert commentary on the specific WD-TSA-UF model in the provided sources.
Dedicated user reviews and specific feedback are not available in the provided data.

