Quick Answer:
If cold tap water looks cloudy or white, it is often harmless air or tiny particles. Start by checking more than one faucet and watching a clear glass: if the cloudiness clears from the bottom up and tiny bubbles rise, it’s probably air. If the same appearance shows at many fixtures or it contains visible particles, treat it more seriously and follow the steps below.
Why This Happens
Common causes include:
- Air in the pipes after work on the water main or a sudden pressure change, which makes very small bubbles that give water a milky look.
- Sediment or mineral particles disturbed in pipes or in a water heater or softener.
- Fixture issues such as a clogged aerator or debris in a faucet.
- Less commonly, contamination from an issue in the supply—if the problem is widespread or accompanied by a smell, taste, or health symptoms, treat it as potentially serious.
For related situations, see White particles in hot water if the hot taps show flakes, and Cloudy water only in morning if it happens at certain times of day.
Step-by-Step What to Do
Step 1 — Compare fixtures
Compare cold water from multiple fixtures to see if milky color is isolated. Test several sinks, an outdoor hose if available, and bathrooms. If only one tap shows the issue, the problem is likely at that fixture.
Step 2 — Run the cold tap
Run the cold water for 30–60 seconds. Note whether the cloudiness clears while running. If it clears, it may be trapped air or a temporary disturbance from recent work on the plumbing or water main.
Step 3 — Fill a clear glass and watch
Fill a tall, clear glass and watch for a few minutes. If the cloudiness slowly lifts and bubbles dissipate from bottom to top, it’s almost certainly air. If particles settle to the bottom, that indicates sediment.
Step 4 — Check aerators and screens
Unscrew the faucet aerator (on taps that have one), inspect for debris, rinse it, and run the tap without it. Many cases of cloudy water at a single sink are solved by cleaning or replacing the aerator.
Step 5 — Note timing and recent changes
Think about whether the problem started after nearby water work, a new appliance, or maintenance. If it appears only at certain times (for example, after the water sits overnight), that pattern helps narrow the cause.
Step 6 — If whole-house or persistent, take action
- If every fixture shows milky or discolored water, contact your local water utility to ask about recent work or reported issues.
- If the issue is limited to your home and persists after flushing pipes, call a licensed plumber for diagnosis and testing.
What Not to Do
- Do not drink milky cold water until cause is known.
- Do not assume it is safe if it looks clear after running without confirming the cause when particles or odors are present.
- Do not use strong chemicals or do DIY repairs you are not comfortable with—call a plumber for persistent problems.
When to Call a Professional
- The appearance is in every tap or neighbors report the same problem.
- There are visible particles that do not settle or there is an unusual smell or taste.
- Household members experience illness or you have vulnerable occupants and the cause is unknown.
- Flushing and basic checks (aerator, comparing fixtures) don’t resolve it.
Safety Notes
- Air in water is not a health risk, but you cannot tell air from contamination just by looking—use the steps above to check.
- If you suspect contamination (odors, color other than white, or health symptoms), stop using the water for drinking and food prep and contact the water utility or a plumber.
- Boiling water removes biological contamination but won’t remove air; only boil if advised by health authorities or your water supplier.
Common Homeowner Questions
- Is cloudy water dangerous? If it’s caused by air bubbles it’s harmless; if particles or odors are present, treat it as potentially unsafe until tested.
- How can I tell air vs sediment? Let the water sit—air bubbles will rise and clear, sediment will settle to the bottom.
- Who should I call first? If multiple homes are affected, call your water utility; if it’s just your house, call a licensed plumber.
For more related articles, see the White Particles, Cloudy Water, or “Milky” Water hub.