If you unscrew the tip of a bathroom or kitchen faucet and find a crust of white flakes packed into the screen, you are looking at a common small problem in many St. Louis homes. The aerator is the little mesh insert that mixes air into the stream and keeps the flow smooth. It catches whatever moves through the pipes, so the flakes can come from several sources. The fix depends on which source is involved, so take a few minutes to test and look before you soak or scrub the screen.
What the flakes usually are
Most white, chalky buildup is mineral scale. Many water supplies in and around St. Louis are described as hard, which means they carry dissolved calcium and magnesium. When water is heated, some of those minerals come out of solution and stick to surfaces. That is why hot water faucets often clog faster than cold ones. Scale in an aerator tends to be crumbly and off-white, and it may fizz a little when a drop of mild acid touches it.
Other sources are also common. Sediment shows up as gritty tan, gray, or dark particles that rinse out of the lines after street or pipe work. Debris can also come from your own plumbing projects. Worn parts, such as small rubber or plastic bits from a flexible hose or washer, can end up in the screen as well.
Test before you clean
Cleaning without knowing the cause often brings the clog back within weeks. Work through these checks first.
- Note which faucets clog. If only the hot side of one sink clogs, scale near the water heater or at that faucet is the likely cause. If every faucet in the house clogs, the source is probably at the main or in a shared line.
- Run cold water into a clean clear glass and hold it up to a window or light. Look for particles that settle at the bottom. Settling grit points toward sediment.
- Test hardness with a home test strip or kit. Collect water from a hot tap and a cold tap the same way each time, then write down the results. Hard readings on both sides, with heavier scale on the hot side, fit normal mineral buildup.
- Watch for sudden changes. A quick drop in flow across the whole house after street or main work often points to sediment or debris moving through the lines.
- Look closely at the screen itself. Small black or colored bits that do not dissolve point to parts that are wearing down.
What to do with the results
- Scale on the hot side with hard readings: soak the aerator in a mild vinegar solution, rinse it, and brush it with an old toothbrush. Wear gloves and keep the room ventilated. Avoid wire brushes, which can scratch the screen.
- Grit in the glass: let cold water run at each tap for a while, then clean the aerators again. If the grit keeps appearing, ask your water provider whether recent work in your area may have stirred up material in the main.
- Flow changes across the whole house: call a licensed plumber, and describe what you saw and when it started.
- Worn parts: replace the aerator, hose, or washer with a matching part.
Why the annual report helps
Your water provider publishes an annual water quality report with general information about the supply. It often describes hardness, which gives you a useful baseline for comparing what you see at home. It does not replace testing at your own tap, because plumbing inside your house can change what reaches the faucet.
Keep the screen clean after you find the cause
Once you know the source, clean the aerator on a regular schedule, especially if your water is hard. Rinse the faucet tip after cleaning and check the flow. If flakes return quickly even after you have addressed the source, the cause may be inside the plumbing. A plumber can look at the water heater, shutoff valves, and the lines near the faucet to find out where the material is coming from.