I'm an 18 year old girl and I love swimming with my girlfriend. When the need to pee we like to have cuddle in the water and we just pee through our swimming costumes. No one can tell what we're doing but the two of us and I love the way the water warms up when she starts to go and then it gets even warmer when I start going.
Oh and the dye they're supposed to add to the pool to show when you pee is a myth as the water doesn't change colour. Even when two of us with full bladders let go in water.