Do not use disposable plastic water bottles. They are not only bad for the environment but unhealthy. And they are expensive.
For one thing, plastic water bottles are bad for the environment. There are several reasons why. Number 1: They are made of plastic. Plastic, the polymer that holds together the modern world and is made from oil. Plastic, the material that is also not very recyclable. In addition to the fact that only about 1% of plastic water bottles are actually recycled, when plastic is recycled, the recycled plastic objects are of worse quality, and usually can not be recycled again.
Number 2: Hardly any of them are recycled, and the caps can not be. See above.
Now, for how disposable water bottles are unhealthy: The plastic contains BPA which is very bad for human development. The BPA leaks out of the plastic into the water especially if the bottle gets warm or is used multiple times.
And the cost: I think this is sort of self explanatory.
However, never fear! Although most reusable plastic water bottles also contain BPA, there are a plethora of companies that make and sell metal watter bottles that come in a variety of prints and colors!