RO vs. Distillation: Why We Don’t Recommend One of Them
On paper these two look like rivals. Both strip almost everything dissolved out of water. Both leave you with something close to pure H₂O. And distillation is the older, simpler, cheaper-sounding one — boil it, catch the steam, done.
So here’s our position up front, since we’re a site that sells water systems and this is the one we don’t offer: distillation is not a household water supply. Not because it doesn’t work — it works beautifully — but because of what it costs you in time and energy to make a gallon. Where it is right, it’s exactly right, and we’ll be specific about where that is.
Two different physics, same result
Reverse osmosis pushes water under pressure against a dense membrane. The water crosses; most dissolved contaminants can’t. It’s a separation, and it happens at the speed your water pressure allows.
Distillation is a phase change. You boil water into steam, leaving the dissolved contaminants behind in the pot, then condense the steam back into liquid. Whatever couldn’t evaporate simply isn’t in the water anymore.
Different mechanisms, remarkably similar catch lists: lead, arsenic, nitrate, fluoride, dissolved salts, hardness, PFAS. These two are peers, not a hierarchy — anyone telling you RO is the gold standard and distillation is primitive has it wrong. It just isn’t the physics that decides this one.
The thing distillation famously misses
That single fact undoes the “boils away everything” intuition. Distillation removes what can’t evaporate. Things that evaporate easily come along for the ride.
Side by side
| Reverse osmosis | Distillation | |
|---|---|---|
| Mechanism | Pressure across a dense membrane | Phase change — boil, then condense |
| Dissolved contaminants | Broad — lead, arsenic, nitrate, fluoride, salts | Broad — essentially the same list |
| VOCs | Partial | Passes them unless paired with carbon |
| Speed | Enough for a drinking tap on demand | Slow — hours per batch |
| Volume | Practical for household drinking & cooking | A few quarts at a time |
| Energy | Little — uses your existing pressure | Hungry — boiling water takes real power |
| Waste | Wet brine, continuously, to a drain | Solid scale residue you wipe out |
| Needs | Water pressure, a drain, under-sink space | A countertop and an outlet |
| Minerals | Strips them — see remineralization | Strips them too; famously flat taste |
| Consumables | Membrane and cartridges | Almost none |
Why we don’t list distillation as a filtration solution
Not flagged with a warning. Removed. Because distillation isn’t an “option” in the sense that someone choosing a household water system means by the word — any more than boiling water or buying bottled is. A machine that produces a few quarts over several hours, using real electricity each time, is not a water supply for a house. Leaving it in the list while explaining at length why you shouldn’t pick it is just a slower way of wasting your time.
You’ll still find the distillation method page on this site, because the chemistry is real and worth understanding. What you won’t find is a recommendation to run your kitchen on one.
Where distillation is genuinely the right answer
Two places, and in both it beats RO outright.
Distilled water as a product, in small volumes. CPAP humidifier reservoirs, steam irons, humidifiers, car batteries, certain appliances that scale up and die on mineral content. These want mineral-free water, they want a quart or two at a time, and nobody cares that it took three hours. A countertop distiller is exactly right for this — and it beats buying jugs of distilled water forever. This is a specific job, well matched to the machine.
Off-grid, where RO’s tradeoffs invert. This is the interesting case. RO needs pressure you may not have, and it discharges wet brine continuously — often several gallons down the drain per gallon made. If you’re managing your own water and your own wastewater, that’s not a minor inconvenience; it’s a real problem with nowhere to put it. Distillation’s waste is a solid scale residue you wipe out of a pot once. And the materials can be nearly free — a solar still or distilling over a fire needs gear you may already own, where RO means buying membranes and replacing them. Slow and energy-hungry stops mattering as much when the energy is sunlight and the alternative is a system you can’t run anyway. Our off-grid guide is where that craft lives.
The short version
They remove the same dissolved load by completely different physics, and neither is the more advanced one. For a household drinking tap, RO wins on the only axis that matters day to day — it makes water at the speed you actually use it. For a couple of quarts of mineral-free water for an appliance, or for a homestead where a wet brine discharge is a problem you can’t solve, distillation isn’t a compromise. It’s the better tool. And in either case, if VOCs are in your water, distillation needs carbon beside it.
Whichever way this goes, it starts the same place: find out what’s actually in your water.