iSpringRO100 5-Stage Under-Sink Reverse Osmosis System, 100 GPD
Five-stage under-sink RO system rated at 100 GPD with a 1:1 pure-to-waste ratio and US-made filters and membrane.
$320
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Usability
Usability
The RO100 stands out in iSpring's range on two points: US-made filters and membrane, and a 1:1 pure-to-waste ratio that halves the water a conventional RO system sends to drain. It is a traditional five-stage under-sink system rather than a tankless unit, and iSpring does not publish an NSF certification listing for it, so the certified-figure buyers should weigh that against the efficiency and domestic-filter advantages. Nothing independent covers this model in any form, which is unusual even by the standards of this brand: no publication, no channel, no measurement, on either the RO100 or its alkaline sibling. So the US-made claim and the 1:1 ratio both rest entirely on iSpring's own account of them. At 100 GPD it produces a fifth of what the tankless models do, and on a tanked system that shows up as a slow refill rather than a slow faucet. Buy it for the waste ratio and the domestic supply chain, and price the absence of third-party evidence into the decision.
- US-made filters and RO membrane
- 1:1 pure-to-waste ratio wastes half the water of a conventional system
- Five-stage RO reduces a broad range of contaminants
- 1-year warranty with lifetime support
- Standard cartridge format is easy to source and service
- Lower price than the tankless RO500 line
- No published NSF/ANSI certification listing
- 100 GPD output is lower than the 500 GPD tankless units
- Traditional layout takes more under-sink space than a tankless system
- Warranty is 1 year and requires registration
- Municipal water only; well water needs pre-treatment
- Flow depends on supply pressure without an added booster pump
The iSpring RO100 is a five-stage under-sink reverse osmosis system rated at 100 GPD with a 1:1 pure-to-waste ratio. Water passes through a sediment filter, a granular activated carbon filter, a carbon block filter, a 100 GPD RO membrane, and a post-carbon polishing filter. iSpring notes the filters and RO membrane are made in the U.S.A.
The 1:1 efficiency is the headline: it sends roughly one gallon to drain per gallon produced, twice as efficient as a conventional 1:3 system. It carries iSpring's 1-year warranty with lifetime support.
iSpring does not publish an NSF/ANSI certification listing for the RO100, so its contaminant reduction is described from manufacturer specifications. It is intended for municipal tap water.
Additional information
Specification: iSpring RO100 5-Stage Under-Sink Reverse Osmosis System, 100 GPD
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Questions answered from our data

How long do iSpring filters last?Of the 24 iSpring systems we list, 24 state a filter life; the most common is 6-12 months (22).
How much does a reverse osmosis system cost?The 69 reverse osmosis systems we list run from $165 to $3,779, with a median of $367.
How long do reverse osmosis filters last?Of the 69 reverse osmosis systems we list, 64 state a filter life; the most common is 6-12 months (62).
Does reverse osmosis remove fluoride?63 of the 76 reverse osmosis systems we list claim to reduce fluoride.






