If your reverse osmosis (RO) water appears white or cloudy, it's almost always due to the presence of tiny air bubbles in the water, rather than a contaminant.
Understanding the Cloudiness: Air Bubbles
The most common reason for your RO water to look white is trapped air. Most likely, the cloudiness is due to air in your source water, as the RO system itself does not create air. When water passes through the RO membrane and into the storage tank, any dissolved air in your source water can get through and collect, forming countless tiny bubbles that give the water a milky appearance.
Why Air Appears in Your Water
Water quality, including its dissolved air content, can change over time. Your municipal or well water supply experiences variations in pressure, temperature, and treatment processes. These changes can cause more air to become dissolved in the water, or for dissolved air to come out of solution as tiny bubbles.
- Pressure Changes: When water is under higher pressure (like in your home's pipes), more air can dissolve into it. When this water is dispensed from your RO system, the pressure drops, causing the dissolved air to form visible bubbles.
- Temperature Fluctuations: Cold water can hold more dissolved air than warm water. As cold water warms up in your pipes or RO tank, the air becomes less soluble and forms bubbles.
- System Operation: Newly installed RO systems or systems that have recently had their filters changed might initially have more air trapped within the lines, which will dissipate over a short period.
How to Confirm It's Air
It's easy to determine if the white appearance is due to air bubbles:
- Fill a Clear Glass: Pour a glass of the cloudy RO water.
- Observe Over Time: Set the glass down and watch it for a few minutes.
- Watch for Clearing: If the cloudiness begins to clear from the bottom up, it confirms that the milky appearance was caused by air bubbles rising and dissipating at the surface.
Identifying Air Bubbles in RO Water
| Observation | Explanation |
|---|---|
| Water appears milky white | Primarily caused by air in your source water that has passed through the RO membrane and collected in the tank. |
| Clears from bottom up | A definitive sign that the cloudiness is due to dissolved air bubbles slowly rising to the surface and escaping. |
| Cloudiness eventually vanishes | Indicates a temporary presence of air, often linked to changes in water pressure, temperature, or recent system maintenance. |
What to Do About It
Since air bubbles are harmless, there's usually no immediate action required. It may have air for a while and then clears up on its own.
- Patience: Often, the issue is temporary and resolves itself as water conditions stabilize.
- Allow to Settle: Simply let your dispensed water sit for a few minutes before drinking, and it will clear.
- Check for Air in Water Heater (if relevant): If the issue is persistent and affects all your cold water, not just RO, check for air in your main water supply or water heater, though this is less common for RO-specific issues.
The white appearance of your RO water is a common and benign phenomenon, indicating air, not impurities.
