Www.winnipesaukee.com has a great depth of well water options.
Oops...
that could have been worded better.
Well, these
www.winnipesaukee.com links might
pinpoint exactly the solution to your water problem.

One problem was traced to a dead mouse in the well!
However, reading the following links is a form of
schadenfreude for us on lake water: because there were never any Radon issues—and no longer any MtBE issues—you might want to switch to lake water for better quality water!
http://www.winnipesaukee.com/forums/...ead.php?t=4060
http://www.winnipesaukee.com/forums/...ad.php?p=87614
http://www.winnipesaukee.com/forums/...ad.php?p=86962
http://www.winnipesaukee.com/forums/...ad.php?p=97370
http://www.winnipesaukee.com/forums/...ead.php?t=7097
http://www.winnipesaukee.com/forums/...ad.php?p=40777
http://www.winnipesaukee.com/forums/...ad.php?p=38694