These two technologies are not competing with each other the way RO competes with a carbon block filter. Both remove dissolved contaminants that carbon filters can’t reach. The real question is which one fits your situation.

How Reverse Osmosis Works

Pressure forces water through a semipermeable membrane with pores at 0.0001 microns. At that size, dissolved salts, minerals, and most molecules are physically excluded. Contaminants concentrate in a reject stream and go down the drain. Clean water collects in a storage tank.

RO systems typically pair the membrane with a sediment pre-filter, one or two carbon pre-filters (removes chlorine that would damage the membrane), and a carbon post-filter for taste. The multi-stage setup handles both chemical and physical contamination.

How Distillation Works

Water is heated to boiling. Contaminants with boiling points higher than water (180°F+) stay in the boiling chamber. Steam rises, travels through a condenser, and collects as purified water. Most bacteria, viruses, dissolved minerals, and heavy metals can’t follow the steam.

Simple in principle. Energy-intensive in practice.

What Each Removes

RO (NSF 58 certified systems): PFAS (90-99%), fluoride (85-96%), arsenic (94-99%), nitrates (70-80%), lead (95-99%), dissolved minerals, bacteria, and most viruses.

Distillation: dissolved minerals, bacteria, viruses, heavy metals, nitrates, most synthetic chemicals. Less effective on volatile organic compounds.

The VOC exception matters. Chloroform, benzene, and other VOCs have boiling points close to water. Some of them volatilize during heating and can carry over into the distillate. A home distiller without a carbon post-filter may not remove VOCs reliably, and in some cases can concentrate them slightly.

RO paired with carbon pre-filtration handles VOCs better than distillation alone.

The Energy Question

This is where the practical difference hits hardest.

A countertop distiller uses 600-1,000 watts and runs for 4-6 hours to produce 1 gallon. At an average U.S. electricity rate of $0.13 per kWh, that’s roughly $0.05-0.10 per gallon just in electricity.

RO is pressure-driven. It uses your home’s water pressure. Operating cost is essentially zero beyond filter and membrane replacement, which comes out to $0.01-0.02 per gallon.

For a household filtering 2 gallons per day, distillation adds $3-6 per month in electricity. Not ruinous, but real.

Speed

An under-sink RO rated at 75 gallons per day is ready when you turn the tap. A countertop distiller produces 1 gallon in 4-6 hours. For families, that math doesn’t work without careful planning.

Water Waste

RO generates 2-4 gallons of reject water per gallon of filtered output. That water isn’t wasted in the sense that it goes down the drain, but it does increase your water bill slightly. Some households use reject water for plants or cleaning.

Distillation produces no reject water but uses significant electrical energy instead. The trade-off depends on whether you’re conserving water or electricity.

PFAS Removal: Where RO Has a Clear Edge

For PFAS specifically, RO outperforms distillation. Short-chain PFAS compounds (PFBS, PFPeA, and others) have lower boiling points and can partially survive distillation. NSF 58 and NSF P473 certified RO systems have documented 90-99% removal rates for both long-chain and short-chain PFAS.

If PFAS is your primary concern, the NSF certification documentation behind quality RO systems is stronger than what most distillers offer.

When Distillation Makes Sense

Very specific purity needs: CPAP machines, dialysis-adjacent home use, laboratory applications, or photography chemicals. These applications require near-zero TDS and benefit from the essentially complete mineral removal that distillation provides.

Off-grid or emergency use where electricity is available but water pressure isn’t. A distiller can run on a generator.

Households where water waste is a bigger concern than energy cost.

The Recommendation

For a household filtering drinking water daily, especially with PFAS, fluoride, arsenic, or nitrate concerns, under-sink reverse osmosis is the better fit. Faster output, lower operating cost, stronger documented PFAS removal, and better VOC handling with carbon pre-filtration.

Distillation is the right call for CPAP water production, specialized purity applications, and situations where you specifically need near-zero TDS without RO infrastructure. For daily drinking water at scale, the energy cost and slow output make it a less practical choice.

Check the water filter decision guide if you’re still working out which contaminants you’re targeting.