Reverse osmosis and distillation arrive at similar looking water by opposite routes: one pushes water through a membrane and leaves contaminants behind, the other evaporates water and leaves contaminants behind. The differences that matter at home are speed, energy, what each misses, and which one you would actually want to drink every day.
How each one separates
Reverse osmosis applies pressure to force water through a membrane that rejects most dissolved material, producing continuously into a storage tank and sending a concentrate stream to drain. Distillation boils water and condenses the vapour, leaving dissolved solids and most contaminants in the boiling chamber. That means distillation handles anything that will not evaporate, while reverse osmosis handles anything the membrane rejects, and the two lists are similar but not identical.
What each one misses
Distillation's blind spot is compounds that boil at or below water's boiling point and travel over with the steam, which includes some volatile organic compounds. Good distillers address this with a vent or a carbon post filter, and that post filter is worth confirming rather than assuming. Reverse osmosis rejects dissolved material well but its performance depends on the membrane's condition, which declines gradually, so it needs the check of comparing feed and product readings to stay trustworthy.
Speed, energy and running cost
Reverse osmosis runs on line pressure and needs no power in a conventional under sink installation, producing steadily into a tank so water is available on demand. Its consumables are prefilters annually and a membrane every few years, and it sends a reject stream to drain. Distillation is slow, measured in hours per batch, and uses a meaningful amount of electricity because it boils every drop. Its maintenance is descaling the boiling chamber, which on hard water is a frequent chore.
Which to choose
For everyday household drinking water, reverse osmosis with a remineralization stage is the practical choice: on demand, no power, and water that tastes like water rather than flat. For appliances that scale, steam irons, humidifiers and similar, distilled water bought or made is often the specified requirement. For a household wanting a broad reduction with a specific contaminant in mind, check which technology the laboratory result actually calls for. Our reverse osmosis guide covers the household systems.
Questions people ask about reverse osmosis vs distilled water
Which produces purer water?
They are comparable in dissolved content. Distillation can pass volatile compounds that travel with the steam unless a carbon post filter is fitted.
Which is cheaper to run?
Reverse osmosis in a conventional under sink installation, since it uses line pressure rather than electricity. Distillation boils every drop.
Do both taste flat?
Yes, because both remove the minerals that give water its taste. A remineralization cartridge on a reverse osmosis system restores it.
Which should I use in a steam iron?
Distilled water is the usual specified requirement for appliances where scale matters, and it is commonly bought rather than made.