Boiling water is a mass of pros and cons. By boiling it, you lose some of the water and thus the toxins are more concentrated. If there are parasites or bacteria, they may be killed by boiling. But if there are chemicals or harmful solids in the water, they will just become more concentrated.
The only way to get really pure water is to make it yourself at home (plastic containers from stores always leach into water). I use the Millenium distiller from Waterwise - it's what is used by the Peace Corps all over the world. It was just under $400 but has paid for itself many times over.
A good and cheap alternative - filling up containers at the RO station at your grocery or drug store. Very cheap and a great improvement on tap water. The chlorine and fluoride alone in tap water are compelling enough toxins to switch.