Black, dense mineral in well water

[JoePeri]

Weird question... Apologies in advance.

I have a 10-year old well and live in the upstate NY area. Houses in my neighborhood sit on a lot of shale, and the area is rocky (right near the Shawangunk Ridge -- see here for some pics of the area http://en.wikipedia.org/wiki/Shawangunk_Ridge ).

Every few months or so, for the past decade, a sink in my house or my clothes washing machine will develop a reduced flow. This is due to a dark, fine, sand-like mineral substance that builds up behind the aerator or supply line strainer.

This stuff is heavy. For example, after I rinse out the aerator in the sink, this black sand will sit in the bottom of the sink and will need a lot of manual agitation to get it to swirl down the drain.

The thought suddenly occurred to be that this stuff might be lead or some toxic metal. It is definitely heavier than regular sand or typical soil particles. The original water analysis done when I bought the house did not indicate a problem though with anything like that.

So today I captured some of this "black sand" in a plastic cup and was thinking about trying to have it analyzed, although I was not sure where to send it.

Anyway, I suddenly had the idea of touching a magnet to the stuff. Well, all of this "black sand" stuff flew right to the magnet. So it must not be lead then, since I think only iron based compounds are attracted to magnets, right?

If it is indeed some form of iron, then it should be safe, correct?

 

[Ballvalve]

"Black sand" is exactly what we call it in the mountains of California when panning for gold in streams that are almost always grey shale based. I am no geologist but its almost as heavy as gold and thats what remains in your pan with the gold. Its not toxic at all but your pump impellers are going to suffer over time. Put in a 20 micron filter and MAINTAIN it. Put up a savings account for the next pump.

You might lift the pump up a bit, as the magnetic "sand" will obviously settle below it. You might also throttle back your pump if possible so that its moving the minimum GPM - the heavy sand should be less likely to be ingested by the lower suction rate. Maybe a CSV is in order here.

If the influx continues, you may need to "blow" youor well out and add a screen or perforated liner.

You might also try panning the local streams for a bit of gold to supply this new savings account.

 

[Sponsor]

 

[JoePeri]

Interesting info Ballvalve. Do you know if that sand out in the Californian prospector's pan is attracted to magnets?

I have not noticed any gold flecks mixed in with the black sand stuff, too bad!
NY is not known for gold deposits, although I suppose gold is in many places in concentrations too low to be seen.

My well is 225 feet deep, but I think the pump is sitting at about 170. I had to have it pulled once since the installer didn't put tape on a stretch of wire and it broke after time due to flexing when the motor kicked on and off. And the guy that did the work told me it wasn't all the way down.

So there is plenty of space below the pump it for stuff to settle. No doubt it is slowly filling over time?

When this pump dies (it is going on 13 years old), I'll make sure we get a filter on the next one.