Reverse osmosis system vs Whole-house system
Reverse osmosis purifies drinking water at one tap (removing fluoride, arsenic, dissolved solids). A whole-house system treats all water for chlorine and sediment but not those health contaminants. For contaminated drinking water, RO wins; for whole-home chlorine and scale, whole-house wins.
| Reverse osmosis system | Whole-house system | |
|---|---|---|
| Best for | You want the most thorough filtration — the only common type that removes fluoride, arsenic, and dissolved solids. Accept some water waste. | You want every tap and shower treated — best for chlorine, sediment, and taste across the whole home. |
| Typical cost per gallon | ~20¢ | ~1¢ |
| Removes fluoride / arsenic | Yes | No |
| Most contaminants certified | up to 17 | up to 3 |
| Installation | Under-sink system with a dedicated faucet and storage tank. | Point-of-entry install on the main line. Usually a plumber. |
| Filter changes / year | ~1 | ~1 |
| Certified models we track | 130 | 154 |
Still not sure? The right choice depends on what's actually in your water. Look up your ZIP to see your contaminants, then pick whichever type is certified to remove them at the lowest cost per gallon.
Frequently asked
Is reverse osmosis system or whole-house system better for lead?
Both can be certified for lead — what matters is the specific model's certification, not the category. Look for NSF/ANSI 53 lead certification on the exact model. We list the certified claim for every filter.
Which is cheaper over time?
Compare cost per gallon, not sticker price. Here, Whole-house system is typically cheaper per gallon (~1¢ vs ~20¢), because the running cost of replacement cartridges usually outweighs the upfront price.