Is it a bad thing to drink a lot of water before, during and after workouts? I've heard that it prevents you from losing any weight, is this true?

Not at all
As your water intake increases, your body decreases production of ADH and aldosterone (water-retaining hormones). This causes you to excrete any water that you drink that isn't needed for proper body functioning or to maintain hydration.

if you have a heavy regimen you're following, you should drink at least 1 oz for every pound of weight on you now. water has NO calories, and you're probably burning plenty in your workout.

No, if your getting a good work out where your working up a sweat then you need that water to keep you hydrated. Plus if you drink enough you feel full which keeps you from pigging out later.

No it i not true because when you sweat u lose weight and the water makes you sweat

NO
You need to drink to stop dehydration

that is false. water is actually a good thing to have while exercising it keeps you hydrated. The weight you gain from water is temporary. It comes out of your body through sweat and pee.

Well, it's water weight. While it is important to stay hydrated, I don't think too much water can make you not loose weight. If you are loosing it, it's being replaced with water (which is heavier) and which would explain a lack of weight lost. All things in moderation. Good luck!

will keep you hydrated anyway and we need to drink like 68oz. a day