A faucet that suddenly runs weak, sprays sideways, or sputters often has a simple cause at the very tip of the spout. Most faucets have a small screened fitting called an aerator. It mixes air into the stream and helps control flow, and mineral particles, sediment, and bits of debris can collect in its screen. In St. Louis homes, where water conditions vary by neighborhood and by the supply that serves the house, this part is one of the first things worth checking before you assume the faucet itself has failed.
Confirm the problem is at one faucet
Start by checking whether other fixtures in the house have the same problem. If every tap is weak, the cause is more likely at the main shutoff, a pressure issue, or a partly closed valve, and a single aerator will not explain it. If only one sink or one side of a double sink is affected, you are in the right place.
Next, compare hot and cold. If only the hot side is weak, check the hot supply valve under the sink, then the aerator. If both sides are weak at the same faucet, the aerator is still the first suspect.
Look at the spray before taking anything apart
Run the faucet briefly and watch the stream. A pattern that is uneven, split, or angled to one side often points to a clogged or partly blocked screen. Many homeowners also see small white flecks or grit landing in the sink, which suggests mineral or sediment buildup.
Remove and clean the aerator
- Wrap a cloth or a layer of tape around the aerator body so pliers do not scratch the finish.
- Turn the aerator counterclockwise by hand first. If it is stuck, use gentle pressure with the wrapped pliers.
- Before you touch anything else, take a photo of the parts in the order they come out. Aerators stack several small pieces, including a screen, washers, and sometimes a flow restrictor, and the order matters when you reassemble.
- Lay the parts on a clean towel. Rinse each piece under running water, keeping debris from dropping back into the screen.
- Soak the metal and plastic parts in plain white vinegar, then brush the screen gently with an old toothbrush. Avoid abrasive pads on finished parts.
- Rinse again, check that the screen is open, and reassemble in the order shown in your photo.
- Screw the aerator back on by hand, then snug it lightly with the wrapped pliers.
Test the faucet and check the shutoffs
Turn the faucet on at full flow and let it run for a minute. Watch the spray pattern and check for leaks at the aerator joint. If the stream is still weak, look under the sink at both supply shutoff valves. Each should be fully open, with the handle or slot aligned with the pipe. A valve turned partway closed can reduce flow at one faucet even after the aerator is clean.
When the aerator is not the cause
If the aerator is clean and the valves are fully open, the problem may be in the faucet cartridge, a flexible supply line that is kinked or partly blocked, or a issue affecting the whole house. If the weak flow shows up at every tap, the scope of the problem matters more than the single fixture, so treat it as a house-wide question rather than a faucet question.
Keep the aerator clear over time
Cleaning the aerator every few months is an easy habit, especially in a region where mineral deposits are a common household concern. A basic home test kit can show whether your water is hard, which helps you decide how often the screen needs attention. Keep a small brush and a few spare washers in a drawer near the sink so cleaning takes minutes instead of a trip to the hardware store.
Know when to call a professional
If the aerator will not unscrew, the threads look damaged, or water leaks from the base of the faucet after reassembly, stop and consider a licensed plumber. A plumber can safely check cartridges and supply lines without risking the finish or the shutoffs. Bring your notes on what you already checked, along with the photo of the aerator parts, so the visit goes faster.