You can see itCommon

Why is my tap water cloudy or milky?

Good news: cloudy or milky water is usually just dissolved air. A one-minute glass test tells you whether it’s air or something worth looking at.

Health risk: Usually none
Most common on: Cold weather · aerated taps
Typical fix: Often nothing needed

Narrow it down

Fill a glass and wait a minute. What happens?

Do the glass test and tap what you see. The page re-sorts, and the Decoder carries it over.

Likely reasons

Likely reasons for cloudy water

This is the usual order. Do the glass test above and we’ll re-sort it for you.

Dissolved air
Most common
The most common cause, and the best news. Cold water holds more air, and pressure changes at the tap release it as a cloud of tiny bubbles that clear from the bottom up within a minute. It isn’t a health concern, and no filter will change it.
Fine sediment
If it stays cloudy
If the glass stays cloudy rather than clearing, fine suspended particles are the likelier cause, silt, clay or rust flakes. It’s usually a nuisance rather than a health issue, and a sediment pre-filter sized to it clears the water.
Your water heater (hot only)
If hot only
Cloudiness only in the hot tap points at the water heater rather than your supply, sediment stirred up in the tank, or minerals leaving solution with the heat. Flushing the tank usually clears it, no filter needed.

What this means

What this means for you

Changes with your answer above. Then two ways to know for sure.

Most of the time this is dissolved air coming out of solution, especially in cold weather, and it clears on its own. The glass test is the quick tell: if it clears from the bottom up within a minute, you’re done, no filter needed. If it stays cloudy, or it’s only the hot tap, that’s a different, still-small thing worth a look.

The stuff that matters most for your health (lead, nitrate, PFAS) has no smell, color, or taste at all. You can’t notice what you can’t sense, so a test is the only way to know. Two ways to start:

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Ground truth

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A certified lab test is the only way to catch what your own plumbing adds, the water the utility report never sees.

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Decode· Cloudy, milky or hazy water

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Quick questions

The questions people ask next

Is cloudy tap water safe to drink?

Almost always, yes. The usual cause is tiny air bubbles, which are completely harmless. The quick check is to fill a glass and watch it: if it clears from the bottom up in a minute, it’s just air. If it stays milky, or has a smell or taste, that’s worth looking into.

How do I tell air bubbles from real contamination?

The glass test. Air rises and clears from the bottom up within a minute. Fine sediment or other particles stay suspended, or settle to the bottom instead of clearing. Air also has no smell or taste, so if there’s an odor along with the cloudiness, don’t chalk it up to air.

Why is my water cloudy only from the cold tap?

Cold water holds more dissolved air, and the pressure and temperature change at the tap releases it as a cloud of tiny bubbles that quickly clear. It isn’t a health concern. If instead only the hot tap runs cloudy, look at the water heater rather than your supply.

Pages that often come up alongside this one.

These are likely causes based on what people commonly describe, a place to start, not a diagnosis, and not medical advice. For anything health-related, a certified lab test and your local health authority are the ones to trust.

Why is my tap water cloudy or milky?

Fill a glass and wait a minute. What happens?

Likely reasons for cloudy water

Dissolved air

Fine sediment

Your water heater (hot only)