Understanding the Differences in Purity, Minerals, and Use Cases
Distilled water is produced by boiling water into steam and then condensing the steam back into liquid in a separate container. This process removes virtually all contaminants — minerals, bacteria, viruses, chemicals, heavy metals, and dissolved solids. Distilled water has a TDS (Total Dissolved Solids) of nearly 0 ppm.
Distillation is the oldest and most thorough water purification method. However, it's slow and energy-intensive — a countertop distiller typically produces 1 gallon in 4-6 hours using about 3 kWh of electricity.
Filtered water is tap water that has passed through one or more filtration media (activated carbon, reverse osmosis membrane, ceramic, etc.) to remove specific contaminants. The filtration method determines what gets removed and what remains.
Unlike distillation, most filtration methods do NOT remove all dissolved minerals. Reverse osmosis removes 85-95% of dissolved solids, while carbon filtration removes almost none. This means filtered water typically retains some beneficial minerals (calcium, magnesium) that distilled water lacks.
| Property | Distilled Water | RO Filtered | Carbon Filtered |
|---|---|---|---|
| TDS Level | 0-5 ppm | 5-50 ppm | Unchanged (100-500 ppm) |
| Minerals | None | Minimal (5-15% remain) | All remain |
| Bacteria/Viruses | Removed | Removed | Not removed |
| Heavy Metals | Removed | 95-99% removed | Partial (NSF 53 models) |
| Chlorine | Removed | Removed | Removed |
| VOCs/Pesticides | Removed | 95%+ removed | 95%+ removed |
| Fluoride | Removed (>99%) | 85-95% removed | Not removed |
| pH | Slightly acidic (~6.0) | Slightly acidic (6.0-6.5) | Unchanged (~7.0) |
| Taste | Flat, bland | Clean, slightly flat | Improved, natural |
| Cost per gallon | $0.30-0.50 (electricity) | $0.05-0.10 (filters) | $0.02-0.05 (filters) |
| Production rate | 0.2-0.3 GPH | Instant (tank fed) | Instant |
Mineral intake: The WHO has noted that demineralized water (distilled and RO) may contribute to reduced mineral intake, particularly magnesium and calcium. However, in a balanced diet, this contribution from water is minimal (typically <5% of daily intake).
Acidity: Distilled and RO water have slightly lower pH (6.0-6.5) due to dissolved CO₂ forming carbonic acid. This is not harmful — orange juice has a pH of 3.5-4.0.
Leaching: Some studies suggest distilled water can leach small amounts of minerals from containers and teeth. This is not clinically significant for normal consumption.