What is the quality of RO water?

December 31, 2025 •

2 min read

According to the World Health Organization (WHO), water with extremely low concentrations of Total Dissolved Solids (TDS), as produced by reverse osmosis, may be unacceptable to some due to its flat, insipid taste. The quality of RO water is a complex topic, praised for its purity but scrutinized for its lack of beneficial minerals.

Quick Summary

The quality of RO water is exceptionally pure, removing up to 99% of contaminants like heavy metals and bacteria via a semi-permeable membrane. However, this process also strips away essential minerals, affecting its taste and potentially impacting health if not remineralized. Balancing purity and mineral content is key.

Key Points

High Purity: RO water is exceptionally pure, removing up to 99% of contaminants like heavy metals, bacteria, and chemicals.
Mineral-Free: The process also strips water of essential minerals such as calcium and magnesium, which can affect taste and health.
TDS Levels: RO water has a very low Total Dissolved Solids (TDS) count, indicating its high level of purification.
Remineralization Solution: Adding a remineralization filter restores beneficial minerals and balances pH, improving both taste and health.
Balanced Perspective: While beneficial for removing contaminants, the need for mineral supplementation or remineralization should be considered for long-term use.
Water Waste: The RO process is less water-efficient than other methods, though modern systems have improved significantly.

What Defines the Quality of RO Water?

The quality of RO water is primarily defined by its high purity due to the reverse osmosis filtration process. This process uses a semi-permeable membrane to remove dissolved solids and contaminants from water. The resulting water has a very low Total Dissolved Solids (TDS) level, typically below 25 parts per million (ppm), indicating effective removal of substances like salts, metals, and minerals. While this purity removes harmful substances, it also removes beneficial minerals such as calcium and magnesium, classifying RO water as demineralized.

What Contaminants Does Reverse Osmosis Remove?

Reverse osmosis is highly effective at removing a broad spectrum of contaminants:

Heavy metals like arsenic, lead, and mercury.
Chemicals such as chlorine, fluoride, pesticides, and VOCs.
Biological contaminants including bacteria and viruses.
Inorganic salts like sodium and nitrates.
Microplastics.

Benefits and Drawbacks of RO Water Quality

Benefits:

High purity and removal of harmful contaminants.
Improved taste and odor.
Provides clean water in areas with poor water quality.

Drawbacks:

Removal of beneficial minerals.
Can be slightly acidic.
Generates wastewater.
Slower production rate.
Requires regular maintenance and filter changes.

Is RO Water Safe for Long-Term Consumption?

For most healthy individuals with a balanced diet, long-term consumption of RO water is considered safe, as essential minerals are primarily obtained from food. However, those with poor diets or specific health conditions, including children, may be more susceptible to mineral deficiencies. Many modern RO systems address this by incorporating a remineralization stage that adds back beneficial minerals like calcium and magnesium, which also improves taste and pH levels.

RO Water Quality vs. Other Water Types


Feature	RO Water	Distilled Water	Tap Water (Municipal)
Purity Level	Removes up to 99% of contaminants.	Up to 100% pure, boiling and condensing vapor.	Varies by location; removes some contaminants.
Mineral Content	Very low to zero, unless remineralized.	Very low to zero.	Contains minerals, levels depend on source.
Taste	Flat and insipid without remineralization.	Very flat, no taste.	Varies, can have a chemical or mineral taste.
Process	Pushed through a semi-permeable membrane.	Boiled and condensed.	Treated at a municipal plant.
Water Waste	Produces wastewater.	No wastewater.	No wastewater.

Conclusion: Making an Informed Decision

The quality of RO water is characterized by its high purity, effectively removing numerous contaminants. While this provides safe drinking water, the removal of beneficial minerals is a key consideration. Remineralization filters are a common solution to restore these minerals, enhancing both health benefits and taste. The best choice depends on individual needs, local water quality, and dietary habits. In areas with poor tap water, RO systems offer robust filtration. For those with good tap water and a focus on taste without mineral loss, a carbon filter might be sufficient. Understanding the pros and cons allows for an informed decision on water filtration.

Frequently Asked Questions

RO water is highly purified by forcing it through a semi-permeable membrane, removing up to 99% of dissolved solids and contaminants. Tap water is treated at municipal plants but can still contain traces of minerals, chemicals, and other substances.

RO water is typically slightly acidic, with a pH between 5.0 and 7.0, because the process removes the buffering minerals. Many systems include a remineralization filter to raise the pH to a more neutral or alkaline level.

Yes, because RO removes the minerals that give water its taste, it can taste flat or bland to some people. Modern systems with remineralization filters reintroduce minerals to restore a more natural and pleasant flavor.

For most healthy individuals with a balanced diet, the majority of essential minerals come from food. While water is a secondary source, a mineral-rich diet can compensate for the minerals removed by RO filtration.

You can use a TDS meter, a small handheld device, to measure the total dissolved solids in your water. A very low reading (e.g., under 50 ppm) indicates low mineral content. For more precise mineral analysis, lab testing is recommended.

RO water is not hard on healthy kidneys. However, for individuals with pre-existing kidney conditions or electrolyte imbalances, long-term consumption of non-remineralized RO water should be discussed with a doctor.

This depends on personal preference and your specific concerns. While municipal water is regulated, an RO system offers a higher level of purification, removing many contaminants that may still be present. If your primary concern is taste, a simpler carbon filter may suffice.