Learn · Comparisons
No filtration method is universal — each one solves a different problem. This page assumes you've read Water Filtration 101; if the terms below are unfamiliar, start there first.
| Feature | Carbon | Reverse Osmosis | Bottled Water |
|---|---|---|---|
| Primary Purpose | Taste, odor, chlorine reduction | Dissolved contaminant reduction | Convenience, portability |
| Dissolved Solids | Limited | High | Varies by brand |
| Heavy Metals | Limited–Moderate | High | Varies by brand |
| Fluoride & Nitrates | Minimal | High | Varies by brand |
| Ongoing Cost | Moderate — scheduled filter changes | Moderate — scheduled filter/membrane changes | High recurring cost |
| Environmental Impact | Low | Some reject water | High plastic waste |
General comparison based on documented performance characteristics. Individual results depend on source water quality, system maintenance, and specific product specifications.
Carbon vs. reverse osmosis
Carbon filtration is well suited to improving taste and odor and reducing chlorine or chloramine, but it does not meaningfully reduce dissolved solids, fluoride, nitrates, or heavy metals.
Reverse osmosis addresses that broader range of dissolved contaminants — typically reducing total dissolved solids by approximately 90–98%, depending on source water — but requires more maintenance, produces some reject water, and removes beneficial minerals along with contaminants unless paired with remineralization.
Neither is "better." Carbon solves a taste and odor problem. RO solves a broader contaminant problem. The right choice depends on which problem you actually have.
What this means in Houston, specifically
This is what "dissolved contaminants" actually refers to, with real figures rather than a general category:
| Contaminant | Houston's Level | EPA Limit | Carbon Alone | Reverse Osmosis |
|---|---|---|---|---|
| Fluoride | 0.11–0.28 ppm | 4.0 ppm | No reduction | High reduction |
| Nitrate | ND–0.95 ppm | 10 ppm | No reduction | High reduction |
| Arsenic | 1.8–9.9 ppb | 10 ppb | No reduction | High reduction |
| TDS | ~230 ppm | No federal limit | No reduction | 90–98% reduction |
Houston's water is legally compliant on every one of these — none exceed the EPA limit. Arsenic is the one worth understanding precisely: it's sat as high as 9.9 ppb in some reported years, close to the 10 ppb legal ceiling, even though the EPA's actual health goal — the level considered zero-risk — is 0. Legally compliant and zero-risk aren't the same claim, and neither V1 nor Elite address arsenic at all. That's specifically what RO is built for.
More on independent testing, including cost →Reverse osmosis vs. bottled water
Bottled water quality and sourcing varies by brand and batch, and is often not transparent to the consumer — the label rarely tells you what's actually been tested for, or how recently.
An under-sink RO system produces water from a known household source, with consistent quality at the point of use, rather than relying on stored and transported product. Bottled water also carries an ongoing recurring cost and generates plastic waste with every purchase, while an RO system's cost is concentrated in the system itself and its scheduled filter replacements.
Any specific cost comparison — your household's typical bottled water spend versus a system and service plan — is worth working out with your own numbers rather than a general estimate, since actual usage varies widely by household.
A common assumption worth checking
The FDA sets the legal threshold for arsenic in bottled water at 10 ppb — the exact same limit the EPA sets for municipal tap water. Bottled water isn't automatically cleaner; it's held to an identical legal standard, not a stricter one.
Independent testing has found this isn't hypothetical: Consumer Reports found one national brand's arsenic levels ranging from 9.48 to 10.1 ppb — at or slightly above the legal limit — and in a separate test, 11 of 130 bottled water brands tested had detectable arsenic.
A detail worth knowing: two of the best-selling bottled water brands in the country start as municipal tap water, then get treated with reverse osmosis before bottling — the same core technology an under-sink RO system uses directly, at your own tap, without the packaging or the recurring cost.
What NSF/ANSI certifications actually mean
These standards come up throughout this site and on each system's technical specifications — here's what each one actually tests for:
| NSF/ANSI 42 | Aesthetic effects — chlorine, taste, odor, and particulate reduction. What V1 and Elite's sediment and carbon stages are certified under. |
| NSF/ANSI 53 | Health effects — reduction of specific contaminants with direct health implications, such as lead or cysts. |
| NSF/ANSI 58 | Reverse osmosis systems specifically — the standard RO+ will be evaluated under. |
Each is independently verified by a third-party lab, not self-reported by the manufacturer — the same distinction as the accredited water testing labs covered on Water Filtration 101.
A note on documentation
The figures on this page reflect documented performance characteristics — published specifications and recognized certifications such as NSF/ANSI standards. Where performance depends on source water quality or system maintenance, that dependency is stated directly. If you'd like the underlying source for any figure on this page, ask — we'll point you to it directly.
Back to Water Filtration 101 →Systems
Each one is built for a specific water condition — not to fill a price tier. If neither fits, we'll say so.
Built for most municipal water treated with standard chlorine disinfection. Addresses taste, odor, and sediment.
View systemBuilt for chloramine-treated municipal water, using catalytic carbon that standard filters can't match.
View systemService plan
One scheduled visit a year, handled. We check in at six months in your first year just to be sure everything's right — no guessing when a filter is due, no forgetting, no blame when it isn't.
See how the plan works