Drinking water is DEFINITELY great for the skin, but I'm wondering if that friend's brown spots were from breakouts/pimples (I'm not sure, but I'm asking.) If so, this is called post-inflammatory hyperpigmentation (which are very temporary), and it's slightly different that hyperpigmentation from the sun. The spots from the sun run much deeper in the skin and actually are caused from years of damage. They don't show right away, and take years to come through, even though most people say that they sort of show 'overnight'. This is just usually brought out by being in the sun, but they've been 'cooking' for a long time.
In case you do want to try lightening products, there are a few different ways you can go. First and foremost however, you must wear a very good UVA/UVB protection EVERYDAY rain or shine...even if it looks overcast...always
. The spots that had faded with the hydroquinone may have worked, but perhaps you weren't wearing sunblock or if you were, your sunblock wasn't the best at doing what it was supposed to be doing. I can give some suggestions if you're interested.
Anyhow, hydroquinone works (I have seen many, many cases), but some people prefer more natural ingredients. Licorice root, is another good ingredient to lighten as well as kojic acid.
I would also suggest peels and/or exfoliating at home with aha's or fruit enzyme masks...a scrub won't do anything, as it simply cannot--molecularly speaking--penetrate as deeply as an aha or fruit enzyme. Pigmentation cells are trapped on the surface of the skin with the dead skin cells, so with appropriate exfoliation (once to twice weekly) it should help lighten.
Wearing mineral makeup will also help due to its high content in zinc oxide and titanium dioxide (two organic and very good UVA blocks).
I hope this helps and like I mentioned, if you're interested I would be happy to give more specific recommendations.
Feel free to look at some of my other posts for more information!
Esthetician Marcella.