"Kingsley G. Morse Jr. (Delete the D)" wrote in message
It seems to me that using a magnet can reveal if
brown water is caused by rusting, as opposed to
dirt seeping into broken pipes, for example.

Thanks,
Kingsley

Dirt does not seep into water pipe that have 40 to 110 psi of pressure in
them. You can get colored water from a well that sucks up mud, old rusted
cast iron water mains, minerals in the water. Probably a few other reasons
also. If you have a broken pipe, you will probably spot it by the lush
green lawn in that area, the big puddle (summer), or the skating rink
(winter) out by the road.