hair in an onsen

I'm going to japan in October and i've planned several trips to onsen. As a woman, I'm not sure what the etiquette is concerning hair...should it be tied back and kept out of the onsen, or covered completely? Is hot spring water bad for your hair? Plese help!

Is hot spring water bad for your hair?
No. Keeping away your hair from waters is just for a manner.

should it be tied back and kept out of the onsen
It's acceptable.

Other notices:
Never dip your towel in a bathtub.
Wash your body completely before getting in a bathtub. (there're certainly ppl disobeying this rule, but never follow them)

If it'll be your first experience of Onsen, you shouldn't stay in a bathtub for long minutes.
If it has outside-bathtub, it's better to use it. Because of cool air, you'd not get exhausted.

This site is useful. But this says "at least rinse your body", and I strongly suggest "wash your body cleanly".
http://members.shaw.ca/onsen/etiquett.htm

Hot springs actually do contain substances that may not suit your hair. But if you tie it up, you can prevent your hair from falling off in the tub, plus you will look a lot prettier!

By the way, traditionally, you are supposed to get a quick dip in the tub after you wash your private parts but before you wash your whole body thoroughly. Then you wash your body with soap, and then take a longer dip.

If you go to a very small, out of the way place, sometimes there won't be an area to soap yourself up. In this case, take one of the small tub/bucket thingies (they will definitely be there) dip it into the onsen and sloosh yourself repeatedly with the water (but don't let it trickle back into the bath or splash people!!!), paying special attention to your privates, before getting in.

In anyplace that has the facilities to soap up and rinse off first, please do. Even if you were just at a different onsen and are clean as a whistle, still soap up for the sake of appearences. Don't let your hair get in the water, it's rude. You wouldn't be happy to see someone's random hairs floating by while you were trying to relax. You can fold your (smaller) towel and put it on your head or leave it by the side of the bath.

Before re-entering the changing area, wipe yourself semi-dry with the small towel you brought in. Use the big towel that you left with your clothes to dry yourself the rest of the way when you return to the place you stored your stuff.

There are a lot of rules, but you'll get the hang of it quickly. Please don't get hung up on the rules. Relax and enjoy the onsen!!!