I have a 32 oz. cup I fill up and drink at least 2x a day, which is working for me so far. I don't really do anything to reduce water retention, though, and would be interested in what others do.

I don't do anything special. If I'm thirsty, I drink water and I assume my body knows when it needs it. If the urine is completely clear, then I know I drank too much water.

In the first few months of eating low carb, I heard all the scary stories about keto-flu so I purposely drank more water than usual (and salt) but started feeling dizzy all the time whenever I got up from a lying position. Once I stopped drinking all the extra water, the problem quickly went away.

Check out the thread "The Waterfall Diet | Water retention" if you are curious.

In Chinese medicine obesity symtoms are in most cases linked to fluid retention.
Some claim it is the root to overweight.
So eliminating foods that your body reacts to like on many low carb diets, detoxes, raw food diets and so forth relieves us ... Fluid retention can be dangerous - our arteries, organs ... the pressure and stress on our intestines (causing leaky gut and more).