Reverse Osmosis Water Filters vs Distillation: Quality, Health and Cost

When it comes to obtaining pure water, reverse osmosis (RO) filtration and distillation stand as two prominent purification methods. Both technologies effectively remove contaminants from water but operate on fundamentally different principles. RO systems use a semipermeable membrane to filter impurities, while distillation involves boiling water and collecting the condensed vapor. Understanding the distinct advantages and limitations of each method can help consumers make informed decisions about their drinking water. This comparison explores their effectiveness, cost implications, health impacts, and practical considerations to determine which purification method might best suit different needs.

Reverse osmosis is a water purification technology that uses a semipermeable membrane to remove ions, unwanted molecules, and larger particles from drinking water. The process works by applying pressure to overcome osmotic pressure, forcing water molecules through a membrane that traps contaminants on one side while allowing purified water to pass through to the other side.

A typical RO system includes multiple filtration stages: pre-filtration to remove sediment and chlorine, the RO membrane itself, and post-filtration with activated carbon. Modern systems can remove up to 99% of dissolved salts, bacteria, parasites, and most organic compounds. These systems are commonly installed under kitchen sinks, providing on-demand filtered water through a dedicated faucet.

The RO process is highly effective at removing common water contaminants including lead, arsenic, copper, nitrates, and many pharmaceutical residues that might be present in municipal water supplies. However, the membrane also removes beneficial minerals like calcium and magnesium, resulting in demineralized water.

What is Water Distillation?

Distillation is one of the oldest water purification methods, mimicking nature’s hydrologic cycle. The process involves heating water until it reaches its boiling point, collecting the resulting steam, and then cooling it to condense back into liquid form. As water transforms into steam, it leaves behind contaminants that have higher boiling points.

Home distillation units typically consist of a boiling chamber, a condensing system, and a collection container. These systems effectively remove inorganic minerals, most bacteria, viruses, and heavy metals from water. The resulting distilled water is highly pure, containing virtually no dissolved solids.

The distillation process is particularly effective at eliminating microorganisms, heavy metals, and minerals. However, some volatile organic compounds (VOCs) with boiling points lower than water can potentially carry over into the distilled product, though many modern distillers incorporate carbon filters to address this limitation.

Purification Effectiveness Comparison

Both reverse osmosis and distillation achieve high levels of water purification, but they excel at removing different types of contaminants. Understanding these differences is crucial for selecting the appropriate system for specific water quality concerns.

Contaminant Type	Reverse Osmosis Effectiveness	Distillation Effectiveness
Bacteria and Viruses	Very Effective (>99%)	Extremely Effective (>99.9%)
Heavy Metals (Lead, Mercury)	Very Effective (95-98%)	Extremely Effective (>99%)
Minerals (Calcium, Magnesium)	Very Effective (90-95%)	Extremely Effective (>99%)
Volatile Organic Compounds	Effective with Carbon Filtration (90-95%)	Moderately Effective (May carry over)
Chlorine & Disinfection By-products	Very Effective with Carbon Pre-filter (>95%)	Very Effective (>95%)
Pharmaceutical Residues	Effective (85-95%)	Variable Effectiveness

Distillation holds a slight edge in removing biological contaminants and inorganic compounds, while reverse osmosis systems with quality carbon filters may be more effective against certain organic chemicals. For comprehensive purification, some high-end systems combine both technologies.

Taste and Mineral Content

The taste of water is significantly influenced by its mineral content. Both RO and distilled water have distinctly different taste profiles due to their purification mechanisms and resulting mineral composition.

Reverse osmosis water typically has a clean, neutral taste that many users find pleasant. While RO removes a substantial portion of minerals, most systems don’t eliminate 100% of dissolved solids. Some modern RO systems even include remineralization stages that add small amounts of beneficial minerals back into the water after filtration.

Distilled water, by contrast, contains virtually no minerals, resulting in what some describe as a flat or “empty” taste. This complete absence of minerals creates a distinctly different mouthfeel compared to mineral-containing water. Some consumers find this taste initially unusual but adapt to it over time.

From a nutritional perspective, neither RO nor distilled water contributes significantly to daily mineral intake, as drinking water generally provides only a small percentage of dietary minerals. However, for long-term consumption, many experts recommend remineralized water for optimal taste and health benefits.

Cost Analysis

Initial Investment

The financial implications of choosing either system involve considering both upfront costs and ongoing expenses. Initial investment varies significantly between these purification methods.

System Type	Price Range	Installation Complexity
Basic RO System	$150-$300	Moderate (DIY possible)
Advanced RO System	$300-$600	Moderate to Complex
Whole-House RO System	$1,000-$4,000+	Complex (Professional recommended)
Countertop Distiller	$75-$300	Simple (Plug and use)
Mid-range Distiller	$200-$400	Simple
Automatic Distiller	$400-$1,000+	Simple to Moderate

Ongoing Costs

The long-term operational expenses often outweigh initial costs and should be carefully considered before purchasing.

Reverse osmosis systems require regular filter replacements, typically costing $50-$150 annually depending on system complexity. The RO membrane itself needs replacement every 2-3 years ($50-$150). Additionally, these systems waste water during filtration, with standard units using 3-5 gallons of water to produce 1 gallon of filtered water, potentially increasing water bills.

Distillers incur significant electricity costs due to the heating process. A typical countertop distiller uses approximately 3 kilowatt-hours of electricity to produce one gallon of water, adding roughly $0.30-$0.50 per gallon (at average US electricity rates). Many units also use carbon filters that require periodic replacement (around $30-$60 yearly).

For a family of four using 3 gallons of purified water daily, the annual operational cost typically ranges from $150-$250 for RO systems and $350-$550 for distillation, making RO generally more economical for ongoing use.

Environmental Considerations

Both purification methods have environmental implications that environmentally conscious consumers should consider before making a decision.

Reverse osmosis systems create wastewater as a byproduct of filtration. Standard residential systems may discharge 3-5 gallons of water for each gallon produced, though high-efficiency models have reduced this ratio significantly. This wastewater impact may be concerning in drought-prone regions where water conservation is critical.

Distillation systems have a higher energy footprint, requiring substantial electricity to heat water to boiling point. This increased energy consumption translates to greater carbon emissions for grid-supplied electricity. Some estimates suggest distilling water requires 3-5 times more energy than reverse osmosis filtration per gallon produced.

• RO systems create plastic waste from filter replacements
• Distillers have minimal consumable parts but higher carbon footprint
• Both systems may require shipping replacement parts, contributing to transportation emissions
• RO systems with efficiency technology can reduce wastewater to less than 1:1 ratio

Health Considerations

The health implications of consuming RO or distilled water have been subject to significant research and some controversy among health professionals.

Both methods produce demineralized water that lacks essential minerals like calcium, magnesium, and potassium. While humans obtain the majority of minerals from food rather than water, some research suggests potential health impacts from long-term consumption of completely demineralized water.

The World Health Organization has noted that “drinking water should contain minimum levels of certain essential minerals.” Some studies suggest potential negative effects on mineral homeostasis from exclusively consuming demineralized water, though conclusive evidence remains limited. For this reason, many health experts recommend remineralization for both RO and distilled water.

For individuals with specific health conditions requiring ultra-pure water or those with compromised immune systems, the superior pathogen removal of distillation may provide additional safety benefits. However, for general consumption, remineralized RO water offers a balanced approach to both purity and mineral content.

Practical Considerations

Space and Installation Requirements

The physical footprint and installation complexity vary significantly between these systems, affecting their practicality for different living situations.

Reverse osmosis systems typically require under-sink installation with connections to water supply and drain lines. Standard units occupy approximately 1-2 cubic feet of cabinet space. Installation involves plumbing modifications, though many homeowners with basic DIY skills can complete the process. Apartment dwellers may need landlord permission for permanent installations.

Distillers are generally countertop appliances requiring only electrical outlets. They occupy valuable counter space (approximately 1 square foot) but require no permanent installation, making them suitable for renters or those who move frequently. Some larger automatic distillers may need dedicated space and drainage connections.

Production Capacity

Water production rates differ substantially between these methods, affecting their suitability for different household sizes.

Standard residential RO systems produce 10-15 gallons per day of filtered water, storing typically 2-4 gallons in a pressurized tank for immediate use. This continuous production meets most household needs without waiting, though drawing large quantities quickly may deplete the tank temporarily.

Countertop distillers typically produce water at a rate of 0.5-1 gallon per 4-6 hours, requiring advance planning for water needs. This slower production may necessitate storing distilled water in separate containers for daily use, potentially creating additional storage requirements and planning consideration.