What is the pH of reverse osmosis water? Many homeowners want to know the answer before installing a reverse osmosis system. This is a great question because RO systems don’t just remove contaminants; they actually change the pH of your drinking water.
Let’s look at what to know about reverse osmosis water before you buy an RO filtration system. This information is useful if you’re thinking about getting an RO system or even if you already have one at home.
What is reverse osmosis?
Reverse osmosis is a water purification method that pushes water through a semipermeable membrane; this membrane is designed with microscopic pores small enough to allow water molecules to pass through while blocking larger particles and impurities.
This process filters out a majority of contaminants, including dissolved solids, heavy metals like lead, harmful chemicals such as chlorine, and even microscopic particles.
RO filtration typically includes:
- Pre-filtration to remove larger particles
- Carbon filtration to eliminate chlorine and organic compounds
- Membrane filtration, where the actual reverse osmosis occurs
- Post-filtration polishing
- Optional remineralization
» MORE: What Is Reverse Osmosis In-Depth
What is the PH of reverse osmosis water?
Reverse osmosis water typically has a pH between 6.0 and 6.5, which is slightly more acidic than regular tap water (pH 7 and 7.5).
It’s worth noting that RO water initially starts with a neutral pH of 7. However, when exposed to air, the water absorbs carbon dioxide, which forms carbonic acid and causes the pH to drop to between 6.0 and 6.5. This happens because RO water lacks minerals that would normally act as pH buffers, making it sensitive to even small amounts of dissolved CO2.
This is why many modern RO systems include remineralization stages that add beneficial minerals like calcium and magnesium back into the water. Not only does this stabilize the pH levels, but it also improves the taste and makes the water better to drink.
What is the best pH level for RO water?
The best pH level for RO water falls within EPA’s recommended range of 6.5 to 9, which is considered safe and optimal for drinking water.
You can learn more on the EPA Caddis pH page.
Target Range
Many experts recommend maintaining RO water within these parameters:
- Minimum safe level: 6.5
- Maximum safe level: 8.5
- Ideal target: 7.0 (neutral)
pH Scale and RO Water At A Glance
- pH Scale: 0-14
- Pure Water (at 25°C): pH 7.0
- Safe Drinking Water Range: pH 6.5 to 8.5.
- RO Water: Initially ~7.0 but drops to 6.0 to 6.5 due to CO2 absorption.
- Remineralization can stabilize pH and restore beneficial minerals.
Does reverse osmosis affect the pH of water?
Yes.
Just to reiterate: Reverse osmosis affects water’s pH through multiple processes. However, the primary reason for the change in pH is the removal of minerals during the filtration process, which eliminates natural pH buffers from the water.
When RO water comes in contact with air, it can lower the pH to as low as 6.0 within about an hour of exposure. Interestingly, RO water has more capacity to absorb CO2 compared to mineral-rich water.
Several technical factors influence the final pH level of RO water, including the efficiency and condition of the RO membrane. Additionally, the quality of the source water and any post-processing treatments can affect the final pH level.
Effects of Different pH Values on the Human Body
While research continues to evolve, the human body operates within a carefully regulated pH range, with various pH levels believed to have distinct effects on health based on current scientific understanding:
Acidic pH (below 7)
- Increases inflammation throughout the body
- Weakens immune system function
- Impairs nutrient absorption
- Negatively impacts bone health
- Can lead to acid reflux and kidney stones
- Affects muscle function
Neutral pH (around 7)
- Promotes optimal enzyme activity
- Supports proper cellular communication
- Maintains healthy metabolic processes
- Enhances disease resistance
- Facilitates overall bodily functions
Alkaline pH (above 7)
- Supports effective detoxification
- Enhances cellular function
- Strengthens immune system response
- Improves digestion
- Increases energy levels
- Promotes better skin health
Is reverse osmosis water bad for you?
Reverse osmosis water is generally safe to drink.
For those concerned about mineral depletion in reverse osmosis water, many modern RO systems come with optional remineralization filters that restore beneficial minerals like calcium and magnesium.
Water Comparison Table
| Water Type | pH Levels | Mineral Content | Cost (Per Gallon) | Environmental Impact |
| Reverse Osmosis Water | 6.0 – 6.5 (can vary with remineralization) | Low (minimal minerals unless remineralized) | $0.08 – $0.10 (after installation) | Low (if water is consumed sustainably) |
| Bottled Water | 6.5 – 8.0 (varies by brand) | Moderate (depending on source) | $0.50 – $3.00 (varies by brand) | High (due to plastic waste) |
| Filtered Tap Water | 6.5 – 7.5 (depends on filter) | Moderate (retains some minerals) | $0.10 – $0.30 (filter replacement costs) | Moderate (requires filters which are disposable) |
Note: Values shown are approximate and may vary.
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Clean, safe water isn’t just a luxury – it’s essential. Don’t leave your water quality to chance. Contact Water Quality of Las Vegas to schedule your consultation and take the first step toward cleaner, healthier water.
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Disclaimer: The information provided herein is for educational and informational purposes only and should not substitute professional medical advice, diagnosis, or treatment. Readers should not rely solely on this information to make health decisions. Always consult with a qualified healthcare provider regarding specific medical conditions, treatments, and concerns. The accuracy and completeness of this information cannot be guaranteed, and any action taken based on this content is strictly at your own risk.
