Is reverse osmosis water the same as distilled water?

No, though they're close. Both remove the vast majority of dissolved solids, so the end result tastes and behaves similarly. The difference is how: reverse osmosis pushes water through a semi-permeable membrane at room temperature, while distillation boils water into steam and condenses it back into liquid, leaving contaminants behind in the boiling chamber. Distilled water is typically a hair purer (near-zero TDS), but RO is far faster, cheaper to run, and gives you water on demand at the tap.

Which is healthier, reverse osmosis or distilled water?

For everyday drinking they're essentially equally safe — both remove lead, arsenic, nitrates, PFAS, and most other contaminants. Neither contains meaningful minerals, which is why some people add a remineralization stage or get minerals from food. According to the EPA, reverse osmosis is one of the technologies effective at reducing contaminants like lead and arsenic, and distillation achieves the same removal by a different mechanism. For most households RO is the more practical 'healthy' choice because it's easy to use every day.

Does reverse osmosis or distilled water remove more contaminants?

Distillation removes a slightly broader range and gets TDS closest to zero, because boiling leaves behind essentially everything that isn't volatile. Reverse osmosis typically rejects 95–99% of dissolved solids — extremely high, but not quite the near-100% of distillation. In practice the gap is tiny for drinking-water purposes. RO can also struggle with some very small volatile compounds, while distillation can carry over volatile organics unless paired with a carbon filter; most quality systems of either type add carbon to cover that.

Is distilled water or RO water cheaper?

Reverse osmosis is dramatically cheaper to produce. An under-sink RO system makes water for roughly a few cents per gallon and runs automatically, while a countertop distiller uses about 3 kWh of electricity to make a single gallon — often 25–50 cents per gallon in energy alone, plus hours of waiting. Buying distilled water by the jug is the most expensive option of all. Over a year of family drinking water, RO almost always wins on cost.

Can I drink reverse osmosis or distilled water every day?

Yes. Both are safe for daily drinking. The main caveat is that both remove beneficial minerals like calcium and magnesium, so if these are your only water source, get those minerals from a balanced diet or add a remineralization filter. The World Health Organization has discussed demineralized water and recommends mineral intake from food; for most people drinking a varied diet, daily RO or distilled water is perfectly fine.

Which is better for a home aquarium, coffee, or a CPAP machine?

It depends on the use. For CPAP machines and steam irons, distilled water is the traditional recommendation because its near-zero mineral content prevents scale — though RO water works well too. For coffee and espresso, neither pure RO nor pure distilled is ideal because flat, mineral-free water makes weak-tasting coffee; a little mineral content (or a remineralized RO tap) brews better. For aquariums, both are used as a blank slate that you then remineralize to the exact parameters your fish need.

Reverse Osmosis vs Distilled Water 2026: Which Is Better to Drink?

Quick Answer: Reverse osmosis and distilled water both strip out nearly all contaminants, so for drinking they’re about equally pure and equally safe — the real difference is how you get the water. Reverse osmosis (RO) filters water through a membrane at room temperature and gives you purified water on demand at the tap for a few cents a gallon. Distillation boils water to steam and condenses it back, producing water that’s a touch purer (near-zero TDS) but slow, energy-hungry, and made one batch at a time. For everyday home drinking water, RO is the better practical choice; distilled wins only for niche uses like CPAP machines, steam irons, and lab work where absolute mineral-free purity matters.

People searching “reverse osmosis vs distilled water” usually want to know which one is better to drink — and the honest answer is that the water itself is nearly identical. Both remove lead, arsenic, nitrates, PFAS, fluoride, and the dissolved solids that affect taste. Where they genuinely differ is speed, cost, convenience, and a few specialty applications. This guide breaks down exactly how each method works, how pure the result really is, what each costs to run, and which one fits your situation.

Reverse osmosis vs distilled water at a glance

Feature	Reverse Osmosis (RO)	Distilled Water
How it works	Membrane filtration (pressure)	Boil to steam, then condense
Contaminants removed	~95–99% of dissolved solids	~99%+ (near-zero TDS)
Removes lead, arsenic, nitrates, PFAS	Yes	Yes
Speed	On demand at the tap	~4–6 hours per gallon
Energy use	None (uses water pressure)	~3 kWh per gallon
Cost per gallon	A few cents	~25–50¢ (electricity) or store-bought
Mineral content	Near zero (remineralization optional)	Near zero
Best for	Everyday home drinking water	CPAP, steam irons, labs, aquariums
Typical price	~$150–$400 under-sink system	~$80–$200 countertop distiller

By the numbers

According to the EPA, reverse osmosis is among the technologies effective at reducing contaminants such as lead, arsenic, nitrate, and PFAS — the same broad contaminant list distillation handles, just by a different mechanism.
A quality RO membrane rejects roughly 95–99% of total dissolved solids (TDS), while distillation typically gets TDS to near zero — purer on paper, but the difference is negligible for drinking water.
Distilling water is energy-intensive: a countertop distiller uses about 3 kWh of electricity to produce a single gallon, and takes roughly 4–6 hours to do it — versus RO water available instantly at the tap.
The CDC notes that distillation and reverse osmosis are both effective at removing many chemical contaminants, but neither removes minerals you’d then want — which is why both produce demineralized water that some users choose to remineralize.

How reverse osmosis works

Reverse osmosis forces water through a semi-permeable membrane with pore openings small enough to block dissolved salts, metals, and most organic molecules, letting only water molecules through. A typical home RO system pairs that membrane with sediment and carbon pre-filters (to protect the membrane and catch chlorine) and a carbon post-filter (to polish taste), then stores the purified water in a small tank so it’s ready the moment you open the dedicated faucet.

The big advantages are speed and cost: RO runs on your home’s existing water pressure, uses no electricity, and delivers purified water on demand for just a few cents a gallon. It’s almost always installed point-of-use under the kitchen sink, treating only the water you drink and cook with. The main trade-offs are that RO produces some wastewater (modern tankless units are far more efficient than older models), and the water is demineralized — many systems add an optional remineralization stage for taste.

Under-Sink Reverse Osmosis System

Best for everyday drinking water · ~$200–$300

A multi-stage under-sink RO system with sediment, carbon, and membrane stages delivers purified water on demand at a dedicated faucet — the most practical way to get RO-quality water at home. Look for NSF/ANSI 58 certification and, ideally, a remineralization stage for taste.

Check price on Amazon →

For the full ranked list, see our guide to the best reverse osmosis systems, or the newer tankless reverse osmosis systems and countertop reverse osmosis systems if you can’t plumb in under the sink.

How distillation works

Distillation mimics the natural water cycle: it boils water into steam, then condenses that steam back into liquid in a separate chamber. Because contaminants like minerals, metals, and salts don’t evaporate at water’s boiling point, they’re left behind in the boiling tank — so what condenses is exceptionally pure, often near-zero TDS. Good distillers add an activated-carbon post-filter to catch any volatile organic compounds that could otherwise boil off and carry over with the steam.

The result is the purest water you can easily make at home, which is why distilled water is the standard for CPAP machines, steam irons, car batteries, and laboratory use. The downsides are practical: distillation is slow (hours per gallon), energy-hungry (it has to boil every drop), and batch-based (you fill it, wait, and store the output). For drinking water that purity advantage is marginal, but for the specialty uses above, distilled is the traditional pick.

Countertop Water Distiller

Best for near-zero TDS purity · ~$100–$160

A stainless-steel countertop distiller boils and condenses water into a collection carafe, producing near-zero-TDS distilled water with no plumbing required — ideal for CPAP machines, steam irons, and anyone who wants the absolute purest water at home.

Check price on Amazon →

For the full breakdown, see our guide to the best water distillers.

Which removes more contaminants?

In practice, both remove nearly everything that matters for drinking water. Distillation edges out RO on raw purity — boiling leaves behind essentially all non-volatile contaminants, getting TDS closest to zero. Reverse osmosis rejects a very high 95–99% of dissolved solids, which is more than enough for safe, great-tasting water.

Each method has one classic blind spot, and both are usually covered the same way. Distillation can let volatile organic compounds (VOCs) boil over with the steam, and RO membranes can pass a few very small volatile molecules — which is exactly why quality systems of both types include an activated-carbon stage to capture those compounds. The takeaway: a well-built RO system and a good distiller with carbon post-filtration produce water that’s, for drinking purposes, indistinguishable in safety.

Cost and convenience: the real deciding factor

Since the water quality is so close, the decision usually comes down to cost and convenience — and here reverse osmosis wins decisively for everyday use. RO uses your home’s water pressure (no electricity), makes water for a few cents a gallon, and gives it to you instantly at the tap. Distillation uses roughly 3 kWh per gallon and takes hours per batch, putting its energy cost around 25–50¢ a gallon before you account for your time. Buying distilled water by the jug is pricier still and means hauling plastic home every week.

The flip side is upfront simplicity: a countertop distiller needs no plumbing or installation — you plug it in and go — whereas an under-sink RO system requires a (DIY-friendly) install under the sink. If you only need a gallon now and then, or you rent and can’t modify plumbing, a distiller or a countertop RO unit is the easier path. For a household drinking water every day, RO’s running cost and convenience are hard to beat.

How to choose

Want everyday drinking and cooking water? Choose reverse osmosis — on-demand, cheap to run, and purer than almost any other home filter. Start with our best reverse osmosis systems.
Need near-zero-TDS water for a CPAP, steam iron, aquarium, or lab? Choose distillation for the absolute purity. See the best water distillers.
Renting or can’t plumb under the sink? A countertop RO system or a plug-in distiller both work without permanent installation.
Worried about specific contaminants? Both handle lead, arsenic, nitrates, and PFAS — but if you want to confirm what’s in your water first, run a water test kit so you treat the right problem.
Concerned about minerals? Both produce demineralized water; pick an RO system with a remineralization stage, or simply get minerals from a balanced diet.

The bottom line

Reverse osmosis and distilled water are nearly identical in purity and safety — both strip out lead, arsenic, nitrates, PFAS, and the dissolved solids that affect taste. The choice isn’t really about which water is “better,” it’s about how you want to make it. For everyday home drinking water, reverse osmosis is the clear winner: instant at the tap, just a few cents a gallon, and no electricity. Distillation earns its place for specialty uses — CPAP machines, steam irons, labs, and aquarium hobbyists — where near-zero TDS is worth the slower, pricier process. If you’re choosing one system for the whole household, get a quality reverse osmosis system; if you need lab-grade purity in small batches, get a water distiller. And if you’re not sure RO is even the right category yet, see our reverse osmosis vs water filter breakdown.

Prices are approximate and change often — tap any button above to check the current Amazon price.