what's the gray residue in my water

September 19, 2009 6:39 PM

What's the gray residue in my water? We moved into this home (built circa 1985) 2 years ago. After bathwater has drained, you find a silty residue left in the tub. You can't see it in the water itself. Residue looks a bit like the calcium deposits one might find normally, but ranges from gray to sometimes sandy brown. Lately there is also some substance much like this clinging to dishes after the dishwasher runs too.

Have been working with city water company for a whole year -- they tested the water and found nothing of concern; they put a filter into the ground to test water coming into my home and first said it was clear, then on another test they too found gray substance on the filter -- they said it "contains" iron and manganese (but if it contains anything else, they don't know.) They also said that iron and manganese do not pose a health risk. They asked me to scrape up accumulated bits of the residue after each bath so they could test it -- this took a long time as it's hard to get much up at once without it disintigrating -- and then they said it couldn't be tested because there was soap in it (duh!). I'm frustrated and don't know how concerned I should be for my family's health. How would one even know if this was coming from one's own pipes? I was looking into a private lab, but the ones the city recommended are meant for corporate testing. Does anyone know what this stuff might be? I live in central Indiana. If anyone has any insights, I'd be very grateful.

posted by keener_sounds to Home & Garden (5 answers total)

If they're saying they can't test soapy stuff for iron, they're lying. It used to be one of the standard tests we ran at the soap factory I worked at.

Call the private labs again, and tell them the situation, and ask them to recommend a lab that would do it, if they won't.

As far as getting samples, have you tried just getting an inch or two of the tap water from the bath, and letting it evaporate, to see if it still leaves the residue? How about if you boiled down a pot of water?
posted by Green Eyed Monster at 6:55 PM on September 19, 2009

Response by poster: Thank you very much for this, Green Eyed Monster -- I'll try these suggestions.
posted by keener_sounds at 7:54 PM on September 19, 2009

We had a similar sounding mysterious grey substance show up in our water as well. It turned out to be the anode rod in the hot water heater disintegrating. You might be seeing the same thing. Replace the rod and the crud disappeared.
posted by roue at 8:36 PM on September 19, 2009

Response by poster: as a matter of fact, I replaced the aging hot water heater first thing, after the water company said it was probably the disintigrating rod...but the crud continues...
posted by keener_sounds at 8:41 PM on September 19, 2009

Is there a local university... maybe somebody in the chemistry department can help you out?
posted by defcom1 at 7:23 AM on September 20, 2009