Quick Answer:
Seeing cloudy or milky water with small white particles after refilling your water heater is common and is often caused by trapped air, disturbed mineral deposits, or loose scale from the tank. Do a few quick checks at home first: fill a clear glass and let it sit for a minute to see whether the cloudiness rises and clears, compare hot and cold taps, and inspect faucet aerators for white specks. If the cloudiness doesn’t clear, leaves residue, or affects multiple fixtures, a plumber can test the source safely.
Why This Happens
When a heater is drained and refilled, trapped air in the tank and pipes can produce tiny bubbles that make water look cloudy. Sediment and mineral scale that were stuck to the tank walls or heating element can loosen and appear as white particles. If the issue shows up only from hot taps, the heater is the likely source; if it appears on both hot and cold taps, the problem is upstream of the heater.
Other household situations can cause similar cloudiness. For example, refilling after winter work commonly introduces air and loose material — see Cloudy water after winterization for more on that scenario. Well systems and pressure changes can also produce white or cloudy water; see Cloudy water from well system for related issues.
Step-by-Step What to Do
Step 1 — Visual glass test
- Fill a clear glass from the faucet that shows the cloudiness.
- Let the glass sit undisturbed for one minute. If the cloudiness rises and clears from the bottom up, it’s likely air bubbles.
Step 2 — Compare hot and cold taps
- Run cold water into a second clear glass and let it sit the same way. If only the hot water shows particles, the water heater is probably the source.
Step 3 — Check aerators and screens
- Unscrew faucet aerators and showerheads and look for white specks or residue. Clean or rinse them and test again.
Step 4 — Run one fixture briefly
- Run a single hot faucet for a minute to see if water clears. Don’t perform repeated long flushes of the heater—short runs are enough to check changes.
Step 5 — Keep notes and collect a sample if needed
- If the particles persist, note which fixtures are affected and how long the condition lasts. Collect a sample in a clean glass and save it for the plumber if you call one.
What Not to Do
- Don’t assume all cloudiness is harmless air — persistent particles can be minerals or dislodged scale.
- Don’t start flushing the heater repeatedly; extensive flushing without knowing the cause can waste water and may not fix the problem.
- Don’t ignore the issue — if cloudiness persists or leaves residue, have a plumber inspect the system.
When to Call a Professional
- If the cloudiness affects multiple fixtures or both hot and cold lines.
- If particles leave a visible residue on glassware, sinks, or clothing.
- If you notice a change in water smell, color, or taste, or if you’re unsure about bacteria or contamination risks. A plumber can collect safe samples and test for minerals, sediment, and microbial contamination.
Safety Notes
- Avoid drinking water you think may be contaminated until you’re confident it’s clear and odorless. Use bottled water for drinking and cooking if you have any doubt.
- When collecting a sample, use a clean glass and label the time and faucet used. Do not mix chemicals into the sample.
- If a professional recommends disinfection or lab testing, follow their instructions rather than trying chemical treatments yourself.
Common Homeowner Questions
- Can the white particles be dangerous? — Usually they are air or mineral scale; persistent residue or odd smells should be checked by a pro.
- Should I drink the water until it clears? — If you’re unsure, avoid drinking it and use bottled water until the issue is resolved.
- How long should it take to clear? — If it’s air, it often clears in minutes; sediment or scale may take longer and needs inspection if it persists beyond a day.