Black particles can come from three common sources: a broken water filter, a degrading faucet washer or gasket, or a disintegrating black rubber flexible supply line hose (for a water heater, washing machine, or kitchen faucet, etc.).
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- Hard particles that are similar in size and shape and look like large coffee grounds. These particles are probably granular activated carbon (GAC) particles from the inside of a water filter. Replace the filter cartridge or consult with the manufacturer or the vendor who sold it to you.
- Solid rubbery particles at one faucet. These particles could be pieces of an old disintegrating faucet washer or gasket. Particles are likely only present at one faucet and that faucet might already be leaking. Replace the faucet washers and the packing at the ends of the supply lines.
- Small black particles that smear. Particles that are small black specs that can be easily smeared between two fingers and are often called oily or sooty in texture can come from the inside of a flexible hose. These black rubber hoses are covered with a braided stainless steel mesh. Over time, the chloramine in the water causes the rubber to break down. Replace the hose, ideally with a liner that is identified as chemical or chloramine resistant. Black rubber hoses typically have a one-year warranty while the more chemical resistant hoses have a five-year warranty.