1 / 7iSpring US21B 2-Stage Under-Sink Water Filter
The iSpring US21B is a two-stage under-sink filter intended to connect to an existing kitchen cold-water supply. Its carbon-block filtration is claimed to reduce chlorine, rust, sediment, sand, dirt, odor and taste, while the manufacturer says it retains beneficial minerals rather than lowering TDS.
At a glance
- Two-stage filtration with a carbon-block method, marketed as a 7-layer design.
- Connects to the existing cold-water supply and is described as requiring no additional faucet or countertop drilling.
- Manufacturer claims up to 50,000 gallons of filtration capacity and a reusable housing life of 5–10 years.
- The product description says beneficial minerals are retained and TDS is not lowered, unlike reverse-osmosis systems.
Often bought together
Pros and cons
Pros
- The direct connection to standard 3/8″ compression fittings can suit buyers who want filtered water at the existing faucet without adding a dedicated faucet.
- The listed capacity and 9-month filter-life figure give buyers two manufacturer-provided planning references, though actual replacement timing may depend on use and water conditions.
- Reported customer feedback includes favorable comments about water taste, reliability and ease of installation.
Cons
- Installation and cartridge replacement are described by the manufacturer as taking more time and effort than twist-on single-stage filters.
- Customer feedback includes reports of leakage, so careful installation and checking connections are important.
Technical specifications
16 specifications| Brand | iSpring |
|---|---|
| Model | US21B |
| Power configuration | Ac |
|---|
| Dimensions listed | 18"L x 15"W x 27"H |
|---|---|
| Weight listed | 13.93 kg |
| Installation type | Under Sink |
| Connection | standard 3/8″ compression fittings |
| Material listed | Carbon Block |
|---|---|
| Claimed capacity | 50000 gallons |
| Filter life cycle | 9 months |
| Claimed reduction | Reduces Chlorine, Rust, Sediment, Sand, Dirt, Bad Odor, Taste |
| Lower temperature range | 40 °F |
|---|---|
| Maximum flow rate | 15 gpm |
| Operating pressure range | 7-10 psi |
| Upper temperature rating | 100.12 °F |
| Maximum supported water TDS level | 700 |
What to know before buying
Listing details to confirm
The listing's 50,000-gallon capacity and 9-month filter cycle are both stated, but it does not explain how to reconcile those figures. It also lists an AC power source for a filter described as a direct-connect carbon-block system, and gives unusually specific operating limits including 7-10 psi and 15 gpm. Confirm which specifications apply to the selected unit before purchase. The manufacturer describes 5–10 years for the reusable housing, while the title says 10 years.
What’s in the box
Included- System with 2 Filters
- Housing wrench
Who is it for?
A good fit for
- Households seeking an under-sink carbon-block filter for chlorine, sediment, rust, odor and taste reduction at an existing kitchen faucet.
- Buyers who prefer a filter that the manufacturer says retains minerals and does not lower TDS.
- People comfortable with a more involved installation and filter replacement than a twist-on disposable cartridge.
Less suited to
- Buyers seeking reverse-osmosis treatment or a system advertised as lowering TDS.
- Anyone requiring a separate filtered-water faucet, since this model is described as connecting to the existing faucet supply.
- Buyers who need an uncomplicated quick-change cartridge installation.
Customer reviews on Amazon
- 5 stars
65% 65% - 4 stars
12% 12% - 3 stars
6% 6% - 2 stars
6% 6% - 1 star
11% 11%
Customer feedback reports favorable experiences with reliability, installation and water taste, alongside some leakage concerns. Buyers planning a direct-connect installation should pay particular attention to secure fittings, especially since the listed installation and cartridge changes may take more effort than a twist-on filter. The aggregate ratings are generally favorable but include a meaningful range of lower ratings, so experiences are not uniform.
Positive themes
- Customers describe the system as reliable and easy to install.
- Customers report that the filtered water tastes good.
Negative themes
- Some customers mention leakage.
Frequently asked questions
Does the iSpring US21B include a separate faucet?
The product is described as connecting to the existing cold-water supply and kitchen faucet, with no extra faucet required.
What does this filter claim to reduce?
The listing says it reduces chlorine, rust, sediment, sand, dirt, bad odor and taste. These are manufacturer claims, not independent test results.
Does it lower TDS?
The manufacturer says it does not lower TDS and retains beneficial minerals. It is not presented as a reverse-osmosis system.
How often should its filters be replaced?
The specifications list a 9-month filter life cycle, while the marketing text also claims up to 50,000 gallons. The listing does not clarify how use and water conditions affect replacement timing.
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