I had two babies in water and like the other posters on here, the memories of them are haunting - in a good way. I can relive those amazing moments with absolute clarity.
I would not have stayed so calm without the water, it really helped me stay on top of the contractions. (mostly -with a little tantrumming in transition) This meant that I was completely focused and aware at the moment that each baby was born.
Nitty gritty:
If you get in too soon and the MW thinks it is slowing down your labour, she will make you get out again, which I would think might be a bit cold and annoying in the short term. (didn't happen to me)
If you have the pool at home you are guaranteed to have water, but not in a hospital or MLU. Without the water I don't know if I would have coped so maybe have a pain relief plan B if not at home?
I had dc2 in a MLU and was told I was not allowed in the water till I had had a trace for an hour. This was painful - being still and flat on my back in full labour. I was ok because after dc1 I had the firm and absolute belief that the water would solve all my problems and I just had to get through that one hour. Came as a surprise to me though, don't know if this is standard.
Whether at home or in hospital you can be naked in the pool as there will be no one else there but your partner and the MW. I didn't think I would be, but that is what was obviously expected and that is what I did. No one will stop you wearing clothes though if you want to.
You might poo. Oh well. Only at the end though when you are about to have your lovely baby and get out anyway.
you can still do anything you want in the water. My lovely MW brought me toast from a trolley when breakfast came round, about 2 hours before dc2 was born, in case I was flagging. I nibbled it over the side of the bath like a cow. It's not like a swimming pool where you are cut off from civilisation!
Of course: if you don't like it, all you have to do is get out. It's not like an injection, where if it makes you feel sick, you're stuck with it.
We had our dc1 in a pool in the dining room at home. dp said a few days before, "are you allowed to give birth in rented accommodation?" I said, "What's he going to do, put it back in?" you do need to put it on a ground floor though unless you are very very sure about the floor. (There is numerical info about weight-bearing stuff that comes with the pool. We just decided to keep it on the ground floor)