It's hard for a woman to keep her bladder full throughout the session, especially if it is lenghty; women are not able to delay urinating for extended periods like most men. You might want to consider showering at the start, clean up, and then continue from there.
I personally follow these steps when asked for gs:
1. drink large cup of coffee right before session
2. consume optional bottle of beer with client
3. then guzzle atleast a litre of water, 2 if you really wanna impress the dude
You can now play for a good 45 minutes as the bladder slowly fills itself with a veritable bucket of the golden stuff...coffee and beer being a diuretic and all. Also, i find that the longer i hold it, the more i can extend the trickle.
Btw, lebagyptian is my recommendation for an ei/gs provider.
There's lots of urban mythology about urine being medically restorative...it's a load of bunk. Pee is not sterile and if the person has std's, hepatitus or a urinary tract infection and you have broken skin, it's a huge safety risk. However as long as everyone's healthy, it's a perfectly safe activity...just shower well afterwords.
As far as drinking the stuff's concerned, most guys i know simply like to have their mouths overflowing with it...or streamed hard on their cocks while they masturbate...and although i haven't read any medical studies, it seems to me that stomach acids would take care of urine quite nicely if you swallowed.
Also, keep watersports in the tub...clean-up's so much easier.
If golden showers are your bag, why don't you just go out and buy yourself a fan? With a little enginuaty, you could have golden showers for the rest of your life and won't get so much grief over it. Cosco's got them on sale right now. Like the old saying says, "If you want something done, you have to do it yourself" If you like golden showers so much, does that mean your into "mudslides" as well?