My cat is heavily pregnant and drinking alot of water!?

Hi guys, my cat is heavily pregnant, and she has started drinking alot of water!! is this a sign that she is due to give birth? Her back passage has had some fluid coming out about 4 days ago. This is my first time and hers too!! She is going outside to the toilet, and stuff, and she is always close to the house, ie in the front garden, under my living room window, so she will wander off and then come and sit on her spot! i bring her in at night time before i go to bed and she is kept inside til i get up in the morning... I just need to know some signs to know that she is getting close to have her babies. She was booked in to be dressed but it was too late!! tut @ me!! but rest assured that all the kittens have homes booked to my good friends.