Quick Answer:
If the first water drawn appears milky or milky-white, it’s most often tiny air bubbles or loose mineral/sediment that settled in the line. Start by running the tap for 30 seconds and checking the aerator screen. If the cloudiness is only on the hot side, inspect the heater line next.
Why This Happens
- Air in the pipes: Dissolved air can separate when water sits, creating tiny bubbles that look cloudy but clear from the bottom up in a glass.
- Mineral or sediment build-up: Particles from older pipes or a water heater can collect and then wash out when you first open the tap.
- Water temperature change: Warm water holds dissolved air differently than cold water; drawing hot water first after a period of inactivity can appear milky.
- Valve or fitting wear: Rubber bits or corrosion breaking down inside a supply line can cause visible cloudiness or particles.
Step-by-Step What to Do
Run tap for 30 seconds
Turn on the faucet and let it run for at least 30 seconds. Run cold and hot separately if possible. If the water clears within a few seconds or a half-minute, the problem was likely trapped air or settled particles that flushed out.
Check the aerator screen
Unscrew the aerator from the spout, inspect the screen for sediment or mineral deposits, rinse or soak it in vinegar, then reinstall. A clogged aerator often makes water look cloudy or reduces flow.
Inspect the heater line
Compare hot and cold water. If only the hot side is cloudy, inspect the heater line and the water heater. Flush the water heater if you see sediment, and check the hot supply valve and connections for deterioration. If you’re not comfortable with the water heater, stop and call a professional.
Other useful checks:
- Fill a clear glass and watch: if the cloudiness clears from the bottom up, it’s air bubbles.
- Ask a neighbor if their water looks the same — that tells you if it’s a local plumbing issue or municipal.
- Shut off the sink’s supply valves briefly and reopen to see if that changes the appearance.
What Not to Do
- Do not drink cloudy water immediately.
- Do not pour strong chemical cleaners into the sink to “clear” water; that won’t fix supply or heater problems and can be hazardous.
- Do not attempt major water heater repairs if you are unfamiliar with gas or electrical components — call a pro.
- Do not ignore repeated cloudiness, odd colors, or a foul odor — these are signs of a larger problem.
When to Call a Professional
- If the cloudiness persists after running the tap and cleaning the aerator.
- If the water is cloudy only on the hot side and flushing the heater didn’t help — this suggests sediment or a failing component in the heater.
- If you notice particles, a strong odor, staining, or if the tap sputters or the flow is irregular. See also Bathroom sink sputters after shutoff for related troubleshooting steps.
- If you also detect a sewer-like smell coming from the sink area, get help; a trapped drain or a failed trap can be the cause. Read more about Bathroom sink smells like sewer gas in a related guide.
Safety Notes
- Wear gloves and eye protection when removing the aerator or handling debris.
- When working near the water heater, turn off power or gas according to the manufacturer’s instructions before doing any maintenance you’re not trained for.
- If you suspect contamination (odd color, taste, or odor that doesn’t clear), avoid drinking the water and contact your water provider or a plumber for testing.
Common Homeowner Questions
- Why does only the first glass look milky? Usually trapped air or settled particles that flush out when you run the tap.
- Is milky water dangerous? Most often it’s not dangerous if caused by air or minerals, but avoid drinking it until it clears and have persistent issues tested.
- Will flushing the water heater fix cloudy hot water? Sometimes — flushing removes sediment that can cloud hot water, but call a pro if you’re unsure or the problem returns.