Reverse osmosis vs distilled water

Which is better for your drinking water?

Stasis Home Research Every claim on this page is graded against peer-reviewed health research and linked to its primary source.Updated July 2026

Reverse osmosis is the better choice for everyday home drinking water, and distilled water is the better fit for specialty non-drinking uses. Both strip water to very low mineral content and remove the same broad range of contaminants. RO does it at the tap without boiling water or running a still, and its carbon stages catch volatile chemicals a still can carry over.

How do Reverse osmosis and Distilled water differ?

Reverse osmosis and distillation reach the same low-mineral endpoint by opposite routes. Reverse osmosis pushes water through a semipermeable membrane under household pressure, so dissolved metals, salts, PFAS, and most larger molecules are too big to pass and get flushed to the drain. Distillation boils water to steam and condenses it back to liquid, so anything that does not vaporize stays behind in the boiling chamber: minerals, metals, nitrate, PFAS, and microplastic particles. The real gap is on the volatile end. Compounds that boil at or near water's boiling point, some VOCs and disinfection byproducts, can travel with the steam and recondense into the collected water unless the still vents them off first. A certified RO system's carbon stages catch those chlorine byproducts and solvent-type chemicals at the tap. Both methods also strip calcium and magnesium, which is where the minerals question comes up.

Reverse osmosis vs Distilled water, side by side

How Reverse osmosis and Distilled water handle each concern.
Concern	Reverse osmosis	Distilled water
PFAS	Yes RO removed more than 94 percent across long- and short-chain PFAS in a 73-home field study (Herkert et al., 2020), handling the full range more consistently than other filters.	Yes The PFAS acids are not appreciably volatile at water's boiling point, so the bulk of them stay behind in the boiling chamber.
Lead and dissolved metals	Yes A system certified to NSF/ANSI 58 for lead reduction removes the large majority of dissolved lead, typically 97 percent or more, and the sediment pre-stage catches particulate lead flakes.	Yes Metals do not vaporize, so they stay behind in the boiling chamber.
Nitrate	Yes Roughly 75 to 95 percent removal, depending on the membrane and how much nitrate is in the incoming water. Carbon filters do not touch nitrate, and boiling concentrates it.	Yes Nitrate salts are nonvolatile, so distillation leaves them behind.
VOCs and volatile organics	Yes The carbon stages before and after the membrane remove solvent-type chemicals.	Partly VOCs that boil at or below water's boiling point can co-distill and recondense into the collected water unless the still vents them off.
Microplastics	Yes Membrane openings are far smaller than microplastic particles, so RO is expected to remove them. Direct point-of-use RO measurement is still limited, so treat this as expected rather than crisply quantified.	Yes Plastic particles do not vaporize and stay in the boiling chamber.

Pick Reverse osmosis when

You want clean drinking and cooking water at the tap with no daily effort.
You want a plumbed system that supplies household drinking water.
Boiling every gallon, and the electricity to do it, is a cost you would rather not carry.
You have under-sink plumbing access for a point-of-use unit.

Pick Distilled water when

You need very low-mineral water for a specific non-drinking use like a CPAP humidifier, a steam iron, or aquarium top-off.
You have no plumbing access and prefer producing water in batches on a countertop.
You want the volatile fraction gone too: pair the still with venting or a carbon post-filter, since a plain still can carry some VOCs across.

What do Reverse osmosis and Distilled water cost?

An under-sink reverse osmosis unit runs roughly 300 to 1,500 dollars installed, then needs a new membrane every 2 to 3 years and fresh carbon stages every 12 to 24 months. A countertop distiller usually has a lower upfront cost but produces water slowly and draws electricity the entire time it runs, so its ongoing cost lands on the power bill rather than in replacement cartridges. RO also sends some water to the drain as concentrate, and newer high-efficiency units cut that waste substantially.

Common questions about Reverse osmosis vs distilled water

Is reverse osmosis or distilled water better for drinking water?

Reverse osmosis is the more practical choice for everyday drinking water at home. Both RO and distillation produce very low-mineral water and remove the same broad set of contaminants, but RO delivers it at the tap with no boiling, no waiting, and no electric still to run, and its carbon stages catch volatile chemicals distillation misses. Distillation is better suited to specialty non-drinking uses.

Does reverse osmosis or distillation remove minerals, and is low-mineral water bad for you?

Reverse osmosis and distillation both remove most of the calcium and magnesium along with the contaminants, so both make low-mineral water. For someone on a normal diet that is not a health problem. The World Health Organization sets no minimum mineral level for drinking water, because food, not water, supplies the large majority of dietary minerals. The one nuance is magnesium, where tap water can be a meaningful source, so remineralizing RO water is an option, not a requirement.

How does this compare to alkaline water?

Alkaline water sits on a different axis entirely from filtration, so it is not an alternative to reverse osmosis or distillation. It is regular water with a higher pH, from added minerals or an ionizer, and raising pH does not remove PFAS, lead, nitrate, or other contaminants. If your goal is cleaner water, RO or distillation is the relevant comparison. Alkalinity is a taste and marketing claim, and it removes no contaminants.

How does this compare to spring water?

Spring water keeps its natural minerals and is not treated to remove contaminants, so what is in it depends on the source, which makes it a taste choice rather than a way to clean your water. In a study of 101 US bottled waters, spring waters carried more PFAS than purified waters, which the authors attributed to reverse osmosis used in most of the purified products (Chow et al., 2021).

How does this compare to deionized water?

Deionized water is very low in minerals like reverse osmosis and distilled water, but it is not a substitute for either as drinking water. Ion-exchange resin strips out the dissolved ions, and it does not reliably remove uncharged organic molecules or microbes. That makes it common in labs and industry, where the target is ion-free water rather than the health contaminants a home cares about.

Can I replace distilled water with RO water?

For drinking, yes. Reverse osmosis and distillation reach the same low-mineral endpoint and remove the same broad range of contaminants, and an RO system certified to NSF/ANSI 58 is the practical way to get there at the tap. For an appliance that specifies distilled water, follow the appliance: distillation leaves essentially nothing behind, while reverse osmosis leaves a small dissolved residue that can still build scale in a steam device.