Treated as a purchase rather than a chemistry question, reverse osmosis and distillation split cleanly. An RO system is plumbed in, produces water on demand and runs on your water pressure. A distiller sits on a counter, makes water in batches and runs on electricity. That difference in how they deliver decides most households' answer.
Output and waiting
An RO unit fills a small pressurized tank continuously, so water is there when you open the dedicated faucet and refills itself between uses. A countertop distiller produces a batch measured in hours, then stops, and you must remember to start it again. For a family cooking and refilling bottles all day, RO is the one that disappears into the background. For a couple drinking a jug a day, batching is manageable.
Running cost and waste
Neither is free. RO sends a reject stream to the drain, so you use more water than you drink, and you buy prefilters and a membrane on a schedule. A distiller uses electricity to boil every gallon it makes, which is the larger ongoing cost in most homes, and uses no extra water. Cost aside, the failure modes differ: an RO membrane degrades silently while still producing water, whereas a distiller either boils or it does not.
Installation and space
RO wants an under sink cabinet, a cold water tee, a drain saddle or connection, and a hole in the countertop for the faucet, which is an afternoon of work or a plumber's visit. A distiller needs a power outlet and counter space and nothing else, which makes it the practical choice in a rental or where drilling a countertop is not an option. Neither is well suited to whole house duty, though whole house RO exists for specific water chemistry.
Maintenance you will actually do
Be honest about this one, because it decides which system keeps working in year three. RO maintenance is scheduled and easy to forget: prefilters on time, membrane on interval, sanitize when you change it. Distiller maintenance is visible and unavoidable: descale the boiling chamber by hand, which is unpleasant on hard water and gets worse the longer it is left. Our whole house reverse osmosis system guide covers the larger installations if point of use is not enough.
Questions people ask about reverse osmosis vs distilled
Which is cheaper to run, RO or a distiller?
RO is usually cheaper per gallon because it runs on line pressure and buys only filters, while a distiller pays for electricity to boil every gallon.
Does reverse osmosis waste water?
Yes, a reject stream goes to the drain. The ratio varies by unit and by feed pressure, and improves with a permeate pump or a higher efficiency membrane.
Can I use either for the whole house?
Distillers are point of use only. Whole house RO exists but is a large, expensive install used for specific water chemistry rather than as a default.