iSpring US21B-CPB Water Filtration System
- Capacity: 8000 Gallons
- Purification: Reduces Lead
- Install Type: Under-Sink
- Material: Activated Carbon, KDF, GAC
Last refreshed Aug 4, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A long life under sink filter aimed specifically at lead reduction, built for permanent installation rather than portability.
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ASIN: B0DH1WY8FYModel: US21B-CPBCategory: Water Filtration Systems
Overview
The iSpring US21B-CPB is an under sink filtration system rated to reduce lead, with a combined activated carbon, KDF, and GAC filter stack rated for 8000 gallons before replacement.
Being under sink rather than countertop, this system stays out of sight and typically feeds a dedicated faucet. The 8000 gallon rating and multi stage media (carbon, KDF, and granular activated carbon) point to a filter designed for extended service life between changes.
- Reduces lead
- 8000 gallon capacity
- Under sink install type
- Activated carbon, KDF, GAC media, 30.6 lb
Who it's for
Fits households with municipal or well water concerns about lead who want permanent under sink filtration rather than a countertop pitcher or dispenser. Renters unable to modify under sink plumbing should look at a countertop alternative instead.
Pros and cons
- Rated to reduce lead specifically
- 8000 gallon filter life before replacement
- Multi stage carbon, KDF, and GAC media
- Requires under sink installation
- At 30.6 lb it is a larger unit to fit under a cabinet
Performance notes
The multi stage media combination of activated carbon, KDF, and GAC is a common approach for tackling both chlorine taste and heavy metals like lead within one filter stack. An 8000 gallon capacity rating means most households would go a long stretch before needing a filter change, though actual life depends on local water quality and usage.
Specifications
| Brand | iSpring |
|---|---|
| Model | US21B-CPB |
| Dimensions & fit | |
| Weight | 30.6 poundshigher than 95% of 41 water filtration systems |
| Dimensions | 19 × 10 × 26 inches |
| Dimensions | 19 x 10 x 26 in |
| Capacity & performance | |
| Capacity | 8000 Gallons |
| Construction & materials | |
| Material | Activated Carbon, KDF, GAC |
| Compatibility & installation | |
| Install Type | Under-Sink |
| Other details | |
| Purification | Reduces Lead |
Closest rivals on specs
Apec Water ROES-100 Water Filtration System- Weight 30.6 vs 26 pounds (+18%)
Ecoviva WP-RO-600G-W Water Filtration System- Weight 30.6 vs 25 pounds (+22%)
Waterdrop WD-T4-A Alkaline Reverse Osmosis System 450 GPD- Weight 30.6 vs 24.21 pounds (+26%)
Frequently asked questions
What does the iSpring US21B-CPB filter out?
It is rated to reduce lead, using a combination of activated carbon, KDF, and GAC media.
How is it installed?
It is an under sink system rather than a countertop or freestanding unit.
How long does the filter last?
It carries an 8000 gallon capacity rating before replacement.