Hey Gabriele! Thanks for posting and livening up our board:). Off the top of my head I would suggest a wonderful little herb named chickweed. It does wonders for water rentention and bloatedness. You can find it in capsule form, tincture, or as a tea in most health food stores.
I would suggest using it as a tea if you can but capsulss from a trustworthy company will work well for you too. One company I like is Nature's Way. There is another one that comes in a bottle with blue trimming that I tend to like as well - I believe it is Solgar's brand.
For teas, I tend to like Traditional Medicinals or to buy it in bulk.
So I hope this helps!
Leah