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Reverse Osmosis vs Spring vs Distilled Water: What's the Difference (and What's Best)?

By the PureFlow Lab Team·Updated June 2026·9 min read

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Reverse osmosis, spring, and distilled are the three “premium” waters people compare when they want something better than straight tap — and they’re genuinely different. One is purified by a membrane, one comes from the ground with its minerals intact, and one is boiled and recondensed to near-total purity. They differ in how clean they are, whether they keep minerals, how they taste, and what they cost. This guide lays out the differences and tells you which makes sense for daily drinking and for specific uses.

Quick Comparison

Reverse Osmosis Spring Water Distilled Water
How it’s made Forced through a fine membrane Collected from a natural spring Boiled, then steam recondensed
Purity Very high (90–99% of TDS removed) Variable — not purified Highest (near-total)
Keeps minerals? No (unless remineralized) Yes (natural minerals) No
Taste Clean, “flat” unless remineralized Natural, often best Flat / bland
Cost Cheapest at home (on tap) Most expensive (bottled) Moderate (distiller + electricity)
Convenience On tap, unlimited Buying/storing bottles Slow batches
Best for Everyday drinking & cooking Those who want natural minerals Appliances, CPAP, specific uses

Reverse Osmosis Water

Reverse osmosis water is tap water forced under pressure through a membrane so fine it removes 90-99% of dissolved solids — heavy metals, fluoride, nitrates, PFAS, and most contaminants. (See What Is Reverse Osmosis Water? for the full mechanism.)

  • Purity: Very high — among the cleanest water you can have at home.
  • Minerals: Removed along with contaminants, so RO water is “demineralized” and can taste flat — though many systems add a remineralization stage to restore taste and minerals.
  • Cost & convenience: This is RO’s big advantage. Once installed, you get unlimited purified water on tap for pennies per gallon — far cheaper than bottled, with nothing to buy or carry.
  • Best for: Everyday drinking and cooking. RO hits the best balance of purity, cost, and convenience for most households. Choose a remineralizing model if you want the minerals and taste back.

See our best reverse osmosis systems guide for under-sink picks, or the countertop guide for renters.

Spring Water

Spring water comes from an underground source and is bottled (or sometimes collected) with its natural minerals intact.

  • Purity: Variable. Spring water is not purified — it’s filtered for clarity and tested to bottling standards, but it can still contain whatever minerals and trace contaminants the source carries. “Natural” doesn’t mean contaminant-free.
  • Minerals: Its main selling point — natural calcium, magnesium, and other minerals give it taste and a small nutritional contribution.
  • Cost & convenience: The most expensive and least convenient of the three for regular use — you’re buying, carrying, and storing bottles, often in plastic. And bottled water (spring included) has been found to contain microplastics, sometimes in large amounts.
  • Best for: People who specifically want naturally mineralized water and don’t mind the cost. For everyday volume, it’s hard to justify over home RO.

Distilled Water

Distilled water is made by boiling water into steam and condensing it back to liquid, leaving virtually all impurities — and minerals — behind.

  • Purity: The highest of the three. Distillation removes essentially everything, comparable to or purer than RO.
  • Minerals: Fully removed, so distilled water is completely demineralized and tastes flat/bland — the same reason pure RO water does.
  • Cost & convenience: You can make it at home with a countertop distiller, but it’s slow (a few hours per batch) and uses electricity to boil the water. Cheaper than bottled spring water over time, but far less convenient than RO on tap.
  • Best for: Specific uses where mineral-free water matters — CPAP machines, humidifiers, steam irons, car batteries, some appliances, and certain medical or lab needs. Many people use distilled for those and RO for drinking.

If you want to make distilled water at home:

CO-Z 4L Brushed Stainless Steel Countertop Water Distiller

CO-Z 4L Countertop Water Distiller

A popular, affordable countertop distiller (4,400+ reviews) that makes about 4 liters per batch — handy for CPAP machines, appliances, or anyone who specifically wants distilled water without buying it by the jug. ~$96.

Check Price on Amazon →

Head-to-Head: Which Wins?

  • Purity: Distilled ≈ Reverse osmosis > Spring. Distilled is marginally purest, RO is very close, spring isn’t purified.
  • Minerals & taste: Spring > RO/Distilled. Spring keeps natural minerals and taste; RO and distilled are flat unless RO is remineralized.
  • Cost (for regular drinking): RO (cheapest, on tap) < Distilled (distiller + electricity) < Spring (bottled, ongoing).
  • Convenience: RO (unlimited on tap) > Distilled (slow batches) > Spring (buying/storing bottles).
  • Environmental impact: RO (no bottles) and home distilling beat bottled spring water, which generates plastic waste and food miles.

So Which Should You Drink?

  • For everyday drinking and cooking: Reverse osmosis is the best all-around choice — very pure, cheapest per gallon, unlimited on tap. If you miss minerals or taste, pick a remineralizing RO system and you get purity and minerals.
  • For appliances, CPAP, humidifiers, or specific mineral-free needs: Distilled is the right tool. Many homes run RO for drinking and keep a distiller (or buy distilled) for these uses.
  • If you specifically want naturally mineralized water and don’t mind the cost: Spring — just know it isn’t purified, and bottled water carries plastic and microplastic concerns.

For the deeper health angle on demineralized water (RO and distilled), see Is Reverse Osmosis Water Good for You?.

Cost Over Time (The Number That Surprises People)

The per-gallon math is lopsided, and it’s the strongest argument for home RO:

Water Approx. cost per gallon Notes
Reverse osmosis (home) ~$0.05–$0.30 After the one-time system cost; just filter changes
Distilled (home distiller) ~$0.25–$0.50 Electricity to boil + occasional cleaning
Distilled (store-bought) ~$1–$1.50 Plus carrying jugs
Spring water (bottled) ~$1–$4+ Ongoing, forever; plus plastic waste

A household drinking a few gallons a day spends hundreds of dollars a year on bottled spring water — money a home RO system recovers within months and then keeps saving. Over a decade, home RO can be thousands of dollars cheaper than bottled water, while cutting the plastic waste and transport footprint that come with bottles. That’s why the long-term answer for most homes is RO on tap, with distilled reserved for the specific appliance/CPAP uses that need it.

FAQ

Is reverse osmosis water the same as distilled water?

They’re similar in purity but made differently. Distilled water is boiled and recondensed; RO water is filtered through a membrane. Both are highly purified and demineralized. For drinking, they’re comparable — RO is just far more convenient and cheaper to produce at home (unlimited on tap vs slow batches).

Which is healthiest: reverse osmosis, spring, or distilled?

For a person on a normal diet, all three are safe, and “healthiest” mostly comes down to contaminant removal versus mineral content. RO and distilled are the purest (fewest contaminants) but demineralized; spring keeps minerals but isn’t purified. The minerals in water are a small part of your intake versus food, so purity usually matters more — and RO (optionally remineralized) gives you the best of both. See our full health breakdown.

Can I drink distilled water every day?

Yes, it’s safe to drink daily — it’s just very pure and mineral-free, so it tastes flat and contributes no minerals. Some people drink it routinely; others prefer remineralized RO for taste. If most of your minerals come from food (as they do for most people), daily distilled water is fine.

Is spring water purified or filtered?

Spring water is filtered for clarity and tested to bottling standards, but it is not purified the way RO or distillation purifies — it retains its natural minerals and can carry trace contaminants from the source. “Natural spring water” is a source description, not a purity guarantee.

Is reverse osmosis or distilled better for a CPAP machine?

Distilled water is the standard recommendation for CPAP machines and humidifiers, because it’s mineral-free and won’t leave scale. RO water is purer than tap and better than nothing, but for CPAP specifically, distilled is the safe choice — make it with a countertop distiller or buy it.

Why does reverse osmosis and distilled water taste flat?

Because both remove the dissolved minerals (calcium, magnesium, bicarbonates) that give water its familiar taste. It’s harmless — just a taste preference. A remineralizing RO system adds those minerals back if you find pure water too flat.

Is reverse osmosis cheaper than buying bottled water?

Dramatically, over time. After the upfront system cost, RO water runs pennies per gallon versus $1-$4+ for bottled. A family that switches from bottled water to a home RO system typically recovers the system’s cost within months and saves hundreds of dollars every year after — while eliminating plastic waste.

Which water is best for making coffee or tea?

Slightly remineralized RO water is often considered ideal — clean enough to let the coffee or tea flavor come through, with just enough minerals for good extraction and taste. Pure distilled or fully demineralized RO can taste flat in a brew; spring water works but varies by source. Many enthusiasts use remineralized RO for exactly this reason.

Bottom Line

For everyday drinking, reverse osmosis is the best choice of the three — very pure, cheapest per gallon, and unlimited on tap, with the option to remineralize for taste. Distilled water is purest and the right pick for appliances, CPAP, and mineral-free needs, but slow to make and flat to drink. Spring water keeps natural minerals and taste, but it isn’t purified, it’s the most expensive, and bottled water carries plastic concerns. Most well-equipped homes end up using RO for drinking and distilled for specific uses — and skip bottled spring water entirely.

Ready to set up RO at home? See our best reverse osmosis systems guide.

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