Answer Man: 'Black gunk' in city water? Is Asheville water safe to drink?

Today’s batch of burning questions, my smart-aleck answers and the real deal:

Question: With city of Asheville Water, I feel safe drinking it, but should I? Over time it leaves a black, moldy looking gunk in dark crevices of sinks, faucets, tubs. I have not seen this in other places I’ve lived. Worried just a bit.

My answer: Well, you know what they say: If it doesn't kill you, it will eventually. Wait a minute ... is that how that saying goes?    

Real answer: City of Asheville spokeswoman Kim Miller checked in with the city's Water Department for this one.

"In our area there is an airborne bacteria called Serratia Marcesans," Miller said via email. "Due to its abundant presence in the environment, and its preference for damp conditions, it's most frequently found growing in bathrooms."

Just as we like water, so does this bacteria.

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"Like any living organism, Serratia Marcesans, needs water to survive, so it just loves hanging out in those areas your reader pointed out — tile grout, shower corners, toilet water lines, and basins," Miller said.

It's highly unlikely the bacteria in your house is coming from the city's water supply.

"Serratia Marcesans is a 'total coliform' bacteria, and the city of Asheville Water Department tests for it in the water at all three plants each day and throughout the distribution system," Miller said.

Miller said water users with concerns can call the Water Department at 828-251-1122.

I've got to admit that this question threw me a bit initially, because when I Googled Serratia marcesans, the images that came up for it all showed a pink-colored, slimy material. An article on the Gwinnett, Georgia, water page noted that they get questions every year about a "slimy pink substance that sometimes forms in moist areas around their homes. They most frequently observe it in toilet bowls, on surfaces in shower stalls and bathtub enclosures, on tiles, in sinks, and in pet water dishes."

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"The most common cause of this pink 'stuff' is a red or pink pigmented bacteria known as Serratia Marcescens," the article continued. "Serratia bacteria are common inhabitants of our environment and can be found in many places, including human and animal feces, dust, soil, and in surface waters. The bacteria will grow in any moist location where phosphorous containing materials or fatty substances accumulate."

So, I was confused, and I sent the question back to Miller and the city for clarification.

She checked back in with the Water Resources folks, and they said the black mold-like stuff the reader is seeing is most likely Serratia marcesans or a close "cousin" of it.

"It is not a mold but an airborne bacteria," Miller said, citing the experts. "The black/gray/pink/orange/red is the same thing. They just create a different pigmentation depending on what they are feeding on."

To be definitive, the experts said, "Unless the reader has had it tested, and the lab came back and said it was a mold, we believe John's reader is describing Serratia Marcesans."

The city also linked to an article from H2GO, aptly titled, "What is the black /grey/pink/orange slimy stuff in my home? An introduction on Serratia Marcescens."

It states:

"If you are experiencing black/grey/pink/orange stains or slippery residues in the shower, in a toilet, at a tap, or in the washing machine, you do not have a water quality problem, and you need not fear a health issue. These residues indicate the presence of naturally-occurring Serratia Marcescens bacteria, which are commonly seen in our area and is commonly found growing in bathrooms (especially on tile grout, shower corners, toilet water lines, and basins), where it manifests as a black, grey, pink, pink-orange, or orange discoloration and leaves a black or grey slimy film feeding off phosphorus-containing materials or fatty substances such as soap and shampoo residue. This residue is harmless to humans."

You can remove the slimy stains, but it'll take some elbow grease. You have to scrub it hard, and then disinfect the affected surfaces to remove any lingering bacteria, H2GO says.

"Bleach is your best bet since it does double-duty to kill the last of the bacteria and dissolve stubborn stains left in its wake," it states.

Visit the site for more thorough instructions. 

Over the years, Asheville's drinking water generally has gotten good marks for safety and taste, as it mostly comes from two mountain reservoirs, Bee Tree in Swannanoa and the North Fork Reservoir in the Black Mountain area.

But, in years past the city has had to issue several "boil water" advisories because old pipes developed leaks or had infiltration problems.

The online site tapsafe.org, which monitors drinking water reports, states, "Asheville's tap water is generally considered safe to drink as Asheville has no active health based violations of the Safe Drinking Water Act (SDWA) that we are aware of."

Tapsafe.org also noted:

"According the EPA’s ECHO database, from April 30, 2019 to June 30, 2022, Asheville's water utility, City of Asheville, had 2 non-health-based violations of the Safe Drinking Water Act."

This is the opinion of John Boyle. To submit a question, contact him at 232-5847 or jboyle@citizen-times.com

This article originally appeared on Asheville Citizen Times: Answer Man: 'Black gunk' in Asheville water? And is the water safe?