What are the black specks in my tap water?

Here are the three usual suspects, and what the agencies say about each one.

### Rubber from worn plumbing parts

The City of North Miami Beach, a Florida water utility, puts it at the top of the list: "Rubber materials used in plumbing fixtures are the most common cause of black particles in tap water." Faucets, valves and supply lines use rubber washers, O-rings and gaskets. Some flexible supply hoses also have rubber inside a braided cover. As those parts age, small black bits can break off and ride out with the water.

That utility also says chloramine, a disinfectant some cities use, "may cause some types of plumbing fixtures to break down faster than normal." That point matters less in Phoenix. The city says its entire water supply is disinfected with chlorine, not chloramine. Rubber still wears out with age, so it stays on the list here, just without that extra push. If you're in another Valley city, check its water quality report to see which disinfectant it uses.

### Carbon from a water filter

The same utility points to filters next: "Carbon filters attached to plumbing fixtures or used in water pitchers can also cause the presence of black particles." Activated carbon is black, and tiny pieces can pass through into your glass. The utility's fix is to replace the filter as recommended by the manufacturer. If the specks only come from the fridge, a pitcher, or one filtered tap, this is almost certainly your answer. Our page on how often to change a whole-house water filter covers timing for bigger systems.

### Manganese and iron from pipes

Manganese is the metal that turns things black. The EPA's secondary standard for manganese is 0.05 milligrams per liter, and it lists the effects above that as "black to brown color; black staining; bitter metallic taste." Penn State Extension says water with manganese may look clear at first, then form black stains or particles once it meets oxygen. The Minnesota Department of Health adds that manganese "can also create a brownish-black or black stain on your toilet, shower, bathtub, or sink."

Pipes can release these metals when the water gets stirred up. North Miami Beach says black particles can come from iron and manganese "which may come loose from pipe walls after a large main break or major construction." Phoenix describes the same thing in its own system. It says discoloration or sediment may be seen after a water leak repair or after a fire hydrant has been flushed nearby, and that visible particles are generally iron or minerals that were stirred up.

Work through these checks. They're practical steps, not rules from any agency.

1. 1Hot, cold or both? Fill a clear glass from each side. Specks only in hot water point toward the water heater or the hoses connected to it. Specks in both point toward the supply or a part every tap shares.
2. 2One tap or all taps? One tap points to that faucet's washer, cartridge, supply hose or aerator. All taps point to the main line, the water heater, or a stir-up in the city main.
3. 3Any filters? If the specks only come from a filtered tap, a pitcher or the fridge, look at the filter first.
4. 4Any recent work? City crews on your street, a main break or hydrant flushing make metal particles the likely cause. So does recent plumbing work in your own house.
5. 5What do they feel like? Catch a few on a white paper towel and pinch them. Soft bits that smear usually point to rubber. Hard grit usually points to mineral or metal sediment.
6. 6Any black stains? Black rings in the toilet or sink along with the specks point toward manganese, per the EPA and Minnesota Department of Health descriptions above.

### Not every black thing is in the water

Two look-alikes fool people. Black gunk growing in a sink drain or overflow is often a biofilm, not something from the supply. Our page on black slime in drains covers that one. And white or tan flakes are a separate problem, often hard water scale. Phoenix water is hard, and our page on why tap water gets cloudy explains the white stuff.

Most of the time they are a nuisance, not a hazard. Still, the answer depends on which kind you have.

• Rubber and filter carbon: these are bits of a worn part, not something the water picked up from outside. The fix is replacing the part.
• Iron: Penn State says iron is not a health concern in drinking water. Its recommended limit exists because it stains and gives water a bitter metallic taste.
• Manganese: this one has a health side at higher levels. The Minnesota Department of Health says children and adults who drink water with high manganese for a long time may have problems with memory, attention and motor skills. It sets guidance of 100 micrograms per liter for homes where an infant drinks tap water or formula made with it, and 300 for households where no infant drinks it. It also says bathing or showering in that water is not harmful.

So if the specks look like metal, come with black staining, and keep coming back, get the water tested. That goes double if a baby drinks it. If the specks came with brown or yellow water, our page on whether discolored tap water is safe walks through the drinking and showering question.

Match the fix to the cause.

Rubber parts. Find the part and replace it. A single faucet usually means a washer, cartridge or aerator. Specks in all the hot taps can lead to the supply hoses at the water heater. Worn supply lines under sinks and at toilets are a quick swap, and our guide to replacing a toilet supply line shows how. North Miami Beach suggests chloramine-resistant parts if gaskets fail within a few years of install.

Filter carbon. Replace the cartridge on schedule and run water through a new one before you drink from it, following the maker's directions.

Metal sediment after city work. Wait for the city to clear its line, then flush your own taps. North Miami Beach says flushing the system and your taps should resolve particles caused by fixtures or construction. Clean your faucet aerators afterward, since they trap grit. Phoenix says clearing its lines can take several hours.

Manganese that keeps coming back. Test the water, then choose treatment based on the level. The Minnesota Department of Health says water softeners can be an effective way to reduce manganese.

Not sure whether the city or your plumbing is to blame? See whether bad water is the city's problem or yours.

HQ Plumbing & Air replaces worn supply lines and fixture parts, repairs and replaces water heaters, and installs water softening and filtration. We're licensed and insured, and you get an upfront price before any work starts. The estimate is free.