Black particles at a faucet come from a short list: a disintegrating rubber washer or supply hose, manganese in the supply, carbon fines from a new filter cartridge, or mould growing in the aerator. Each looks slightly different and each has a different fix, so identify the material before you spend anything. Catch some on a white cloth and start there.
Rubber: black bits that smear
If the particles are soft, flatten between your fingers and smear rather than crumble, they are almost certainly rubber from a degraded washer, an O-ring or the lining of a flexible supply hose. This is by far the most common cause, and the tell is that it affects one fixture rather than the whole house. Chlorinated water attacks cheap rubber over the years. Replace the supply hoses and the faucet cartridge or washer, and the problem stops permanently.
Manganese: black staining across every tap
If every fixture in the house produces black or dark brown specks, and laundry picks up dark staining, suspect manganese in the source water. Penn State Extension treats iron and manganese as secondary, aesthetic contaminants and gives recommended maximums of 0.3 mg/L iron and 0.05 mg/L manganese. Manganese stains at a much lower concentration than iron does, so a level that looks trivial on a report can still blacken fixtures and laundry.
Carbon fines and aerator growth
A newly fitted carbon filter sheds fine black dust for the first few minutes of use, which is normal and clears after a proper flush of the specified duration. If it persists beyond that, the cartridge is failing and the media is escaping. Separately, a black slime you can wipe off the aerator, the drain rim or the shower head is usually harmless airborne mould feeding on soap residue, not something in the water. Clean it and see whether it returns.
The fix follows the diagnosis
Rubber means a plumbing repair, not a treatment system, and a filter would simply hide it. Manganese means treatment on the incoming line, typically oxidation followed by a media filter, sized on a lab test. Carbon fines mean replacing the cartridge. Mould means cleaning. Where the cause is genuinely in the water, a point-of-use filter still helps at the kitchen tap while you sort the whole-house side out.
Questions people ask about black stuff coming out of faucet
Is black stuff from the faucet dangerous?
Rubber fragments and aerator mould are unpleasant rather than hazardous. Manganese carries an aesthetic standard, but any change in water warrants a test.
Why does it only happen at one tap?
A single-fixture problem points to that fixture's own parts: washers, the cartridge or the flexible supply hoses under the sink.
Will a faucet filter solve it?
It catches particles at that tap but does not stop them being produced, so find the source first or you will simply clog the filter repeatedly.