White crust on the tip of a kitchen faucet is one of the most common things St. Louis homeowners notice, and it is usually a mineral deposit rather than a sign that something is broken. Before you reach for a wrench, it helps to figure out which part is clogged, how the faucet is put together, and whether the problem is in the aerator or somewhere else.
What the white crust usually is
An aerator is the small screened fitting that screws onto the end of a faucet. It mixes air into the stream and keeps water from splashing. Because it is the last thing the water passes through, it collects minerals that come out of solution as water dries. That usually shows up as a chalky white or gray crust on the screen or around the threads. A hard, powdery crust that sits mostly on the metal parts points toward mineral buildup.
Confirm which faucet is affected
Many kitchens in St. Louis have two water sources at the sink: the main faucet and a separate faucet for reverse osmosis drinking water. Check the faucet you are looking at. A scaled main faucet aerator tells you nothing about the filter, and a slow stream from a dedicated filter faucet may have a different cause, such as a restricted feed or a flow restrictor. Note which faucet it is, and whether the stream is weak only on hot, only on cold, or on both.
Simple checks before you remove anything
- Run the faucet for a moment and watch whether the stream is spread, uneven, or spitting.
- Look at the aerator tip for crust, grit, or a loose screen.
- Check the base of the faucet and the area under the sink for drips, since a leak can look like a flow problem.
- Note whether the problem started after a filter change, a plumbing repair, or a change in your water service.
Removing and cleaning an aerator
If the faucet has a standard removable aerator, you can usually clean it yourself. Work slowly and keep the parts in order.
- Take a photo of the aerator and its parts before you take anything apart so you can match the layering when you reassemble.
- Wrap the aerator body in a cloth or tape, then turn it counterclockwise by hand. Use pliers only with the cloth in place.
- Lay the parts out on a towel in the order they came off. Small washers and screens are easy to lose.
- Soak the metal parts in a mild vinegar solution until the crust loosens, then rinse them well with clean water.
- Brush the screen gently with a soft brush. Do not force the screen open or bend it.
- Reassemble in the same order, hand tighten, then run the water and check the threads for leaks.
When the problem is bigger than the aerator
If cleaning the aerator does not restore flow, the restriction may be in the faucet cartridge, the supply line, a shutoff valve, or a filter upstream. Turn off the shutoff valve under the sink before you disconnect anything, and check that the valve turns freely. Older valves that are stiff or corroded may not close fully, so work slowly and keep a bucket under the connection. Stop and call a licensed plumber if you see corrosion on the valve body, a drip you cannot stop, or a cartridge that does not come out cleanly.
Water questions to ask next
A crust that keeps returning soon after cleaning suggests the water carries a fair amount of dissolved mineral. That does not tell you what else is in the water or whether it matters for your household. A home test kit or a certified lab report gives a clearer picture. Water providers serving the St. Louis area typically publish information about their supply, and that is a good place to start if you want to understand where your water comes from. Pay attention to whether the scale changes with the seasons or after a service change in your area.
Keeping the faucet clean going forward
Wipe the faucet tip after use, especially around the threads, and clean the aerator on a schedule you can actually keep. Writing the date on a note inside a cabinet door helps you notice patterns. If scale returns quickly on the same faucet, it may be time to look at the water supply more closely rather than cleaning the same part again.