A recently released study suggesting that it is the way you use the plastic bottle that can be a problem. In some cases, bpa isn't released from the plastic into the water unless the plastic is heated. The water bottle in your fridge might be okay, but the bottle sitting in your hot car is not. Their study suggested that women especially are at a greater risk of breast cancer if they drink bottled water that has been heated.
Be aware as you research this topic that there is a lot of misinformation about plastic bottles. This is a topic with a lot of urban legends as well as true facts.
If you are talking about this in a broader context than just the health context, you can bring in the environmental impact of bottled water. When people drink a lot of bottled water, they are creating a great deal of unnecessary waste. You could typically get water that is just as pure from your faucet (or at worst a filter) without creating all that plastic waste. This is much more "green" than drinking from bottles.
It depends on the type of plastic that you use and the temperature of water.
If you are using bottles made of non-polycarbonate plastic, which contains either polyethylene or polypropylene, there is no danger, even if water has higher temperatures.
The polycarbonate plastic contains a toxin called bisphenol. If the polycarbonate plastic is heated then this toxin is released and even low levels of this toxin could lead to prostate, breast cancer or other dangerous health problems.
Before you panic, you should know that health professionals believe that the amount of toxins from plastic bottles and other plastic items is not dangerous.
The amount of BPA, that is transmitted in foods and drinks stored in plastic recipients, is too small to cause health problems.