You turn on the tap and milky water fills the glass — then watches it clear from the bottom up like a tiny lava lamp. If that sounds familiar, you have probably already searched why is my sink water cloudy and been hit with a wall of conflicting answers. The good news is that nine times out of ten, the cause is harmless trapped air. The other times, the issue points to mineral content, plumbing problems, or supply line work that needs attention.
- The Most Common Cause: Dissolved Air
- How to Tell Air from a Real Problem
- When Cloudiness Means Mineral Buildup
- Hot Water Only: The Water Heater Suspect
- Cloudy After a Pipe Repair or Water Main Work
- Sediment, Rust, and Discoloration
- When to Call a Plumber or Water Utility
- Quick Fixes You Can Try Today
- Frequently Asked Questions
The Most Common Cause: Dissolved Air
If the cloudiness clears within 30 seconds and starts at the bottom of the glass, you are looking at dissolved air bubbles. Cold water holds more air than warm water, and when pressurized water exits a faucet aerator, the pressure drop releases the air as microscopic bubbles. The water looks like skim milk for a few seconds, then clears as the bubbles rise.
This is completely safe. It happens more often in winter when incoming water is colder, after the city flushes hydrants nearby, or when your hot water heater introduces extra air during the heating process. No action needed beyond letting the glass sit for a moment.
How to Tell Air from a Real Problem
Run a simple test. Fill a clear glass with the cloudy water and set it on the counter. Watch the cloudiness:
- Clears bottom-up within 30 seconds — dissolved air, harmless
- Stays cloudy or settles to the bottom as sediment — minerals, rust, or pipe debris
- Takes on a yellow, brown, or pink tint — iron, manganese, or bacterial contamination
- Has a sulfur smell along with cloudiness — anode rod issue or bacterial growth in water heater
The settling test takes 60 seconds and saves you a service call. Repeat with hot and cold water separately, since hot-only cloudiness almost always points to your water heater.
When Cloudiness Means Mineral Buildup
Hard water areas — most of the western United States, the Midwest, and parts of Florida and Texas — see persistent cloudiness from calcium and magnesium scale. The minerals dissolve in your municipal supply, then precipitate out when water is heated or sits in pipes. The result is white scale on faucet aerators and a permanent haze in tap water.
A water hardness test kit costs about $10 and gives you a reading in grains per gallon (gpg). Anything above 7 gpg is hard, and above 10 gpg is very hard. If you test in that range, a whole-house water softener with a capacity of 32,000 to 48,000 grains will solve cloudiness and protect your appliances. Expect to pay $800 to $2,500 installed.
Hot Water Only: The Water Heater Suspect
If only your hot tap runs cloudy, suspect the water heater. Sediment builds up at the bottom of the tank over the years — minerals, rust flakes, and biofilm. When hot water draws from the bottom of the tank, it stirs up sediment and carries it to your faucet.
Drain and flush the heater once a year to slow this process. Shut off the gas or power, connect a garden hose to the drain valve, and run the water until it comes out clear. A 40 gallon tank takes about 20 minutes. If the water heater is over 12 years old and the cloudiness persists after flushing, the tank is likely failing internally and replacement is on the horizon.
Cloudy After a Pipe Repair or Water Main Work
Cloudiness right after the city repairs a water main, or after you have any plumbing work done in your home, is normal for 24 to 48 hours. Air gets pushed into the system when pipes are drained and refilled. Run cold water through every faucet for 5 minutes — start with the lowest and work up — to purge the trapped air. Open the highest faucet last to let the air escape.
If cloudiness persists more than two days after pipe work, call your municipal water utility and ask if there is ongoing main work in the area. Many cities have free water testing for residents.
Sediment, Rust, and Discoloration
When cloudy water settles into a layer of grit or particles at the bottom of the glass, you have sediment in the supply lines. This is most common in homes with galvanized steel pipes installed before 1960. The pipes corrode from the inside out, releasing rust and scale into the water.
A whole-house sediment filter (a 5 micron filter housing costs about $80) installed at the main shutoff catches most of it. Long-term, replacing galvanized lines with PEX or copper is the only permanent fix and runs $4,000 to $15,000 depending on home size.
When to Call a Plumber or Water Utility
Most cloudiness is fixable yourself, but some signs warrant a professional. Call a plumber if:
- Cloudiness persists in cold water after letting it sit for 5 minutes
- Water has a metallic, sulfur, or chemical smell
- You see particles or sediment in every glass for more than 48 hours
- Cloudy water is accompanied by reduced pressure
- Pets or family members are getting digestive issues
Call your water utility if multiple neighbors notice the same problem, or if your water suddenly changes color. Cities are required to provide a Consumer Confidence Report annually that lists what is in your water.
Quick Fixes You Can Try Today
Before assuming the worst, try these no-cost steps in order:
- Unscrew the faucet aerator and rinse out any debris. Soak it in vinegar overnight if it is heavily scaled.
- Run cold water for 5 minutes from the most-used tap.
- Flush the water heater per the manufacturer instructions.
- Check under-sink shutoff valves for partial closure or buildup.
- Test the water hardness with a $10 kit from any hardware store.
These cover the vast majority of cloudy water situations and either solve the problem or point you toward the actual culprit.
Frequently Asked Questions
Is cloudy tap water safe to drink?
Cloudy water from dissolved air is completely safe. Cloudiness from sediment or minerals is also generally safe but unpleasant. Cloudiness with discoloration or smell may indicate contamination — do not drink and contact your water utility.
Why does this happen in winter only?
Cold winter water holds more dissolved air than warm summer water. When the pressurized cold water exits the faucet, the air comes out of solution as bubbles, creating a temporary milky appearance that clears in seconds.
Will boiling cloudy water make it clear?
Boiling removes dissolved air, so air-caused cloudiness will disappear. Boiling does not remove minerals, sediment, or chemical contaminants. For those, you need filtration.
How do I get rid of cloudy hot water?
Flush your water heater. Annual flushing removes the sediment that causes hot water cloudiness. If flushing does not help and your heater is older than 12 years, the tank is likely deteriorating internally and needs replacement.
