White or milky water is often caused by tiny air bubbles formed during pumping, pressure changes or temperature variations within the water system. Because the solubility of oxygen decreases as water temperature increases, dissolved air can form small bubbles when water is warmed or exposed to pressure changes. If the water clears after standing a few minutes in a glass, the issue is typically caused by air bubbles and is generally harmless.
In other cases, white or milky water may be caused by calcium precipitation, other minerals or suspended particles that do not disappear when the water is left standing. If the cloudiness remains after standing in a glass for an extended period, further investigation is recommended.
Common Causes
- Tiny Air Bubbles
- Aeration or Degassing
- Pressure Changes
- Hard Water and Calcium Precipitation
- Mineral Precipitation
Common Symptoms
- Milky or Greyish Water from the Tap
- Water Clears After Standing
- Small Bubbles on the Glass
- White Deposits on Fixtures and Glass
Common Treatment Methods
- Pump and Pressure Inspection
- Aeration and Degassing
- Water Softening
- Filtration
- Water Analysis
Example Treatment Trains
Groundwater
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Water Softening
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UV Disinfection
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Drinking Water
Well Water
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Degassing
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UV Disinfection
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Drinking Water
If the water clears after standing for a few minutes, the issue is often caused by air bubbles rather than contamination. Persistent cloudiness may instead be related to mineral precipitation or other water quality problems. Water analysis and consultation with a qualified water treatment specialist are recommended when the cause is uncertain.