This is Ligonier's friendly neighborhood blog and an attempt to recapture our lively opinionated debates in a free speech zone.

Please join our conversations. Contributors welcome.

Friday, December 13, 2013

response to the moldy water concerns

~ here's a response from a friend he wanted me to send in so you could add it as a comment to the moldy water blog that was posted this week.  Thanks !! 

There can’t be mold in the water if there are no pathogens.  The video showed the water authority has tested and did not find pathogens in the water.  While I’m not saying it is impossible, it is unlikely that the treatment plant is producing water that does not meet US EPA drinking water standards, particularly for pathogens and other primary contaminants. Any entity that delivers drinking water via pipes to homes and businesses is required by law to meet these standards and test for them regularly.  Incidentally, the bottled water that America embraces to the tune of $1 billion/yr has no such testing requirements, is largely unregulated, and is often repackaged municipal water that simply removes the chlorine.  Nevertheless, problems can occur in municipal systems and typically you would be notified if there were problems at the plant or with the chlorine residual.  But, there could always be an unnoticed small pipe break in localized areas that haven’t been tested. The lady should have her water tested out of the faucet to confirm/refute her suspicions.  She should also ask for the water authority’s historic dissolved oxygen and sulfide ion concentration data to see if they were problematically low and high, respectively.

Hard to say for sure just by looking at a video, but it seems to me, the black residue on the toilet is not mold, but rather a precipitate.  The black color tends to indicate a sulfide, likely an iron sulfide precipitate.  This would also explain why she wasn’t able to scrub it off.  Iron sulfide is one of the most insoluble compounds that there is.  Rather than the treatment plant to be at blame, the more likely candidate is water chemistry influences in the distribution system.  If iron sulfide is found, the iron source could be metal piping in her house (common in older houses) or the distribution system (i.e., the water authority’s responsibility).   Usually, water authorities do cathodic protection of metal pipes, but without this, the metal pipes would corrode faster.  Without cathodic protection, even just a slight change in the pH of the produced water could bring these chemicals into solution, and when exposed to the atmosphere in a toilet, precipitate out. 

All I know is I live in Ligonier, and I don’t have this problem.  The water here seems great so far (been here 9 months).  Maybe a little extra iron, but I’ve never seen a sulfide or dark precipitate. 

~ PhD water engineer

I have to add that our office toilets have this dark residue and it wasn't there until this year.  It is very hard to keep a clean toilet at least in this location.