Distilled vs Reverse Osmosis vs Spring Water: What's the Difference?

By Megahome Editorial Team· October 13, 2026 · 9 min read

TL;DR

Distillation and reverse osmosis both significantly reduce a wide range of contaminants; distillation needs no plumbing and leaves almost no dissolved minerals, while RO runs from an under-sink system and sends reject water to the drain. Spring water is a regulated natural water whose minerals depend on its source.

Home distillation and reverse osmosis (RO) are both purification methods that significantly reduce a wide range of contaminants. Distillation removes almost all dissolved minerals and needs no plumbing; RO delivers water on demand from an under-sink system but sends reject water down the drain. Spring water is a natural, regulated bottled water whose mineral content depends on its source — it is not purified in the same sense, and it isn't meant to be.

What is the difference between distilled, RO and spring water?

The three often sit side by side on a supermarket shelf, but they come from very different processes:

Distilled water — water is boiled, the steam rises away from dissolved substances, and the steam is condensed back into liquid. In the US, bottled water may only be labelled “distilled” if it is produced by distillation and meets the US Pharmacopeia definition of purified water.
Reverse osmosis (RO) water — pressure forces water through a semi-permeable membrane. The US Environmental Protection Agency (EPA) describes two streams: treated water (“permeate”) and reject water (“concentrate” or “brine”) that goes down the drain.
Spring water — under the US Food and Drug Administration (FDA) definition, water from an underground formation that flows naturally to the surface, collected at the spring or through a bore hole tapping the same formation. It describes a source, not a treatment.

So distillation and RO are ways of treating the water you already have, while spring water is a water you buy. That is why “which is purest?” and “which suits my household?” are slightly different questions. For a broader look at filters, see distilled water vs filtered water.

Distilled vs RO vs spring water at a glance

	Home distillation	Point-of-use RO	Bottled spring water
How it works	Boil, then condense the steam	Pressure through a membrane	Natural underground source, bottled
Dissolved minerals	Almost all removed (owners report 0–6 ppm TDS)	Largely reduced	Naturally present; varies by source
Bacteria, viruses, parasites	Removed (CDC)	Removed (CDC)	Must meet FDA quality standards (US)
Lead and other metals	Removes lead, arsenic, cadmium, chromium (CDC)	Removes lead, copper, chromium; may reduce arsenic (CDC)	Must meet FDA allowable levels (US)
Volatile organic compounds	Some can carry over with steam; a carbon post-filter helps	Can potentially remove (EPA)	Depends on source and bottler
Installation	None — countertop, plug in	Under the sink, plumbed in	None
Main resource used	Electricity (about 0.8 kWh per litre)	Reject water to the drain	Packaging and transport
Speed	About 4 litres per batch of 5.5–6 hours	On demand from a storage tank	Instant
Regular upkeep	Descaling, carbon sachet	Pre-filters and membrane	Buying, carrying, recycling

Which removes more contaminants: distillation or reverse osmosis?

Both are broad-spectrum methods, and official sources describe them in similar terms. The US Centers for Disease Control and Prevention (CDC) says distillation removes parasites, bacteria, viruses and many chemicals, including arsenic, barium, cadmium, chromium, lead, nitrate, sodium, sulfate, calcium, magnesium and many organic chemicals. For RO, the CDC says it removes parasites, bacteria and viruses and some chemicals, including lead, copper, chromium, chloride and sodium, and may also reduce arsenic, fluoride, radium, sulfate, nitrate and minerals such as calcium and magnesium.

University of Nebraska–Lincoln Extension lists fluoride and nitrate among the substances distillation removes and describes a well-run distiller as removing up to 99.5 percent of impurities. RO results depend heavily on the condition of the membrane and on keeping up with filter changes.

Neither method is perfect. Some volatile organic compounds boil at or below water's boiling point and can travel with the steam — the CDC notes that distillation does not remove some volatile organic compounds, volatile solvents and certain pesticides. That is why Megahome distillers pass the finished water through an activated-carbon post-filter. The EPA, for its part, says RO can potentially remove volatile organic compounds and PFAS. For PFAS specifically, the EPA's home-filter guidance lists RO, activated carbon and ion exchange and advises checking for NSF/ANSI 53 or 58 certification; independent data on home distillers and PFAS is still limited. Our article on fluoride, lead and PFAS goes into more detail.

The practical rule: if you are worried about one specific contaminant, have your water tested first, then choose a system shown to reduce that contaminant.

Is spring water purer than distilled or RO water?

Not in the technical sense — and that is not its purpose. Spring water is valued for its natural character and taste, which come partly from the minerals it picks up underground. In the US, bottled water must meet FDA “allowable levels” for microbiological, chemical, physical and radiological quality, so spring water from a reputable bottler is a regulated, safe drink.

Its dissolved-mineral content, however, varies from source to source. For context, US rules only allow the name “mineral water” when water contains at least 250 ppm of total dissolved solids (TDS). Owners of Megahome distillers, by contrast, report TDS meter readings of about 0–6 ppm on their distilled water. In short: distilled and RO water are the “blank slate” options; spring water is the “natural minerals” option.

How do they compare on waste water, energy and running cost?

Reverse osmosis: water to the drain

According to the EPA, a typical point-of-use RO system generates five gallons or more of reject water for every gallon of treated water, and inefficient units up to ten. Systems carrying the EPA WaterSense label must send 2.3 gallons or less down the drain per gallon treated, and their membrane must last at least a year before replacement. If you choose RO, the WaterSense label is worth looking for.

Distillation: electricity and time

The CDC notes that distillation generally uses more energy and takes longer than other treatment methods. Here is the maths for a Megahome distiller rated at 580 W: 0.58 kW × about 5.75 hours ≈ 3.3 kWh per 4-litre batch, or roughly 0.8 kWh per litre. Multiply that by your local electricity price, or use our cost calculator. There is no drain line and no cooling water — a fan cools the condenser — and only a small residue is left in the boiling chamber to rinse away.

Spring water: no equipment, but bottles

Bottled water needs no machine, but it means buying, carrying, storing and recycling bottles. Distiller owners who switched from bottled water estimate a payback of roughly 3–12 months, depending on how much they used to buy.

What about installation, speed and day-to-day upkeep?

RO is installed under the sink and connected to the plumbing, so it suits homeowners who want filtered water on tap. Pre-filters and the membrane need replacing on the manufacturer's schedule.
A countertop distiller just plugs in, which suits renters and anyone who doesn't want to alter the plumbing. It works in batches — about 4 litres every 5.5–6 hours — and owners mention fan noise and some warmth, so most run it in the kitchen or a utility room. Megahome's manual asks you to descale at least once a month with citric acid and to replace the activated-carbon sachet within 25 days. The unit switches itself off when a batch is done, so no plug-in timer is needed.
Bottled spring water needs no upkeep at all, beyond storing it somewhere cool and away from sunlight.

One shared hygiene point: treated water is pure, not sterile. Keep containers clean and covered, and clean a distiller before restarting it after a few idle days — the CDC notes that bacteria may grow on a distiller's cooling coils when it is not in use.

Which should you choose?

Choose distillation if you want consistently very low-mineral water — for drinking, cooking, coffee machines, steam irons, CPAP humidifiers whose manuals specify distilled water, or aquariums — with no plumbing, and you are happy with batch production.
Choose RO if you need larger volumes straight from the tap and can install an under-sink system; look for the WaterSense label and for certification against the contaminants that matter to you.
Choose spring water if you mainly enjoy its taste and natural minerals and your main concern is flavour rather than a specific contaminant.

Many households mix and match. And if you are wondering about minerals: the WHO's drinking-water guidelines say there is not enough scientific information on the long-term effects of very low-mineral water to make recommendations either way, while Taiwan's Food and Drug Administration notes that food is the main source of minerals in a balanced diet. Read more in is distilled water safe to drink every day?

Megahome has built countertop distillers in Tainan, Taiwan, since 1992. Its MH943T-SW and MH943S-SW models hold TÜV Rheinland GS certificate 50514575, and as of September 2026 Megahome distillers have around 5,000 Amazon ratings averaging 4.5–4.7 stars. You can explore the MH-943TWS or find a local dealer on our where to buy page.

Key takeaways

Distillation and RO both significantly reduce a wide range of contaminants; spring water is a regulated natural water, not a purification method.
Distilled water is almost mineral-free; spring water's minerals vary by source.
RO uses water (typically five gallons or more of reject water per gallon, 2.3 or less with WaterSense); distillation uses electricity (about 0.8 kWh per litre).
Some volatile compounds can carry over in distillation, which is why a carbon post-filter is used.
For a specific contaminant, test first and choose a method proven for it.

Frequently asked questions

Is RO water the same as distilled water?

No. Both are low in dissolved solids, but they are made differently: RO pushes water through a membrane, while distillation boils water and condenses the steam. US bottling rules allow both to be sold as “purified” water, but only distillation can be labelled “distilled”.

Which removes fluoride: distillation or reverse osmosis?

University of Nebraska–Lincoln Extension lists fluoride among the substances distillation removes, and the CDC says RO may reduce fluoride. If fluoride is your main concern, test your water and check the performance data for the system you are considering.

Is spring water safe to drink?

Spring water from a reputable bottler is regulated drinking water; in the US it must meet FDA quality standards. It simply isn't demineralised — its natural minerals are part of its character.

Do I need both a distiller and an RO system?

Usually not. Choose based on how much water you need, whether you can plumb in a system, and what is in your water. Some households use one for drinking and keep distilled water for appliances.

Sources

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