What should well water be tested for?

I'm wondering, what all should well water be tested for, to find out if it's safe for a peat bog. Our water doesn't appear to be real hard. There's not spots on the glasses anyway, and they're washed by hand, no dishwasher here but me... The nitrate level was below the safe drinking water level last time we had it checked. Thanks....

Not necessarily all that important what exactly is in it but how much is in it. Here's the TDS meter I use to test water-
http://www.gamurdock.com/gam/files/documents/HMTDS3.pdf
I don't recall where I bought it but it was cheap enough.

You should be able to go over to a county extension office and they should be able to tell you what the ppm of your water is. Otherwise, why don't you just go to some sort of a place that sells home water purification equipment and ask them to tell you. Try not to contaminate your sample.

Decent explanation of what a TDS meter does here-
http://www.reefkeeping.com/issues/2004-04/rhf/feature/index.php

Thanks Equilibrium, so far i just have rain water in it. Just thinking about next year for the dry season. I sure hope i haven't allowed a fatal mistake to happen. My liner was just a little short on one side. Someone told my husband a roofing caulk, blackjack is what would seal it. So that's what was used. The stuff stinks so bad i cringe with thoughts of the consequences. All of the "hard" work i've put into this peat bog... Washing sand-yuck!! But i did it, (my poor husband, couldn't understand why i would need to wash already washed sand) but he was sure a good egg and didn't really give me much guff. When we got the sand, it happened to be my 51st birthday, the day before was our 31st anniversary too. So he just held his breath for my sake!! ;-) (-; :-) (-: Made me happy.
This site is sure quiet, Everyone must be busy outside. This is unusual for me to spend so much time on the computer, on a quest tho. Now i will check out your links. Thanks again

Am i understanding, that it's the mineral content that i want to be low?

These plants can't handle much. They co-evolved in nutrient defficient environments and they adapted to same. You want your ppm to ideally be around 50. Anything above 100 is no good. And no, minerals aren't good.

Regarding rainwater, not all rainwater is the greatest. Particularly when it hasn't rained in a real long time. I go out and disconnect the lines to my bogs when we've gone without rain for a bit. I disconnect them for the first half hour or so to allow impurities to flush down into the ground. Then I reconnect it and let it rip. Now if we've been getting rain on a regular basis, I don't bother disconnecting anything.

That makes sense about the first rain after a dry spell being full of contaminates. Do you think i'm in trouble with the caulk?

No, it will dry.

I've used Great Stuff before and suffered no ill effects.

Would have been nice if I had spelled deficient above properly. Oops.