Why is my well water cloudy or milky?
What causes this
Trapped air (harmless)
The most common cause of milky-looking water is dissolved air. The giveaway: fill a glass and watch it — if it clears from the bottom up as the bubbles rise and escape, it is just air and is harmless.
Sediment and turbidity
If the glass does not clear, the cloudiness is suspended particles — silt or fine sediment. This can come from a failing well screen, drawing the well down too far, or stirred-up sediment, and is measured as turbidity.
Is it dangerous?
Cloudiness from air is harmless and clears on its own. Cloudiness from sediment is usually an aesthetic and equipment issue, but turbidity can shield bacteria and interfere with disinfection, so persistent sediment is worth a turbidity and coliform test rather than ignoring it.
The test that tells you
A symptom only narrows it down. To know for sure, have a state-certified lab test for:
- turbidity
- coliform bacteria
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How to fix it
Do the glass test first. If it is air, no treatment is needed. If it is sediment, a sediment (particulate) filter sized to the particle load will clear most cases; persistent or worsening sediment calls for a well and pump inspection to check the well screen and pressure tank.
- 1
Do the glass test
Fill a clear glass and let it stand. If it clears from the bottom up as bubbles rise, the cloudiness is harmless air. If it stays cloudy, you have suspended sediment.
- 2
Test for turbidity and bacteria if it is sediment
When the cloudiness is sediment, have a certified lab measure turbidity and coliform bacteria, because turbidity can shelter bacteria and interfere with disinfection.
- 3
Install a sediment filter
Add a sediment (particulate) filter sized to the particle load to clear most cases of suspended silt and fine sediment.
- 4
Inspect the well and pump if it persists
If sediment persists or worsens, have the well and pump inspected to check for a failing well screen or a pressure-tank problem.
A symptom is a clue, not a diagnosis. Only a lab test of your individual well confirms what is in your water — do not assume a symptom is definitely harmless or definitely dangerous until you have tested. The county-level USGS area estimates elsewhere on this site describe a region as a whole and cannot stand in for testing your own well.
By TapWaterData Editorial
Frequently asked questions
Is cloudy well water dangerous?
Often not — the most common cause is trapped air, which is harmless and clears on its own. But cloudiness from sediment (turbidity) can shelter bacteria and interfere with disinfection, so if a glass of water does not clear from the bottom up, it is worth a turbidity and coliform test.
How can I tell if cloudy water is air or sediment?
Fill a clear glass and let it stand. If it clears from the bottom up as bubbles rise to the surface, it is dissolved air and harmless. If it stays cloudy, the haze is suspended sediment, which may come from a failing well screen, the pump, or the pressure tank.
How do I clear up sediment in my well water?
A sediment (particulate) filter sized to the particle load clears most cases of suspended silt. If the sediment persists or gets worse, have the well and pump inspected, because it can signal a failing well screen or a pressure-tank issue.
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