The most common cause of black particles showing up in tap water is the disintegration of rubber materials used in plumbing fixtures. These particles float and often adhere to sinks and bathtubs and can appear sooty or greasy.

Gaskets, hoses connected to water heaters and washing machines, rubber heat traps furnished with some newer water heaters and o-rings can disintegrate over time and some pieces can collect in tubs, toilet tanks, faucets and other locations. Flexible hoses (braided stainless) are often lined with black rubber. Homeowners should make sure they or their plumbers select hose, gasket and water heater components that are compatible with drinking water supply common to southern California.