Water from charcoal filters is better than the tap water in most locations, but as your collection grows, it's worth investing in a good purifier. Light At home in the bogs, there are very few obstructions to sunlight. As such, most CPs require a great deal of light to thrive. A south or west-facing windowsill is usually adequate. If sunlight isn't available in sufficient quantity, I've had very good luck with twin-tube flourescent shop light fixtures.
Some people claim that expensive grow-light tubes are worth the money.
I'm on a budget, so I couldn't justify a twenty-dollar tube over a two dollar tube. Most CPs developed the carnivorous habit due to the highly impoverished soils in which they live. Since they were unable to absorb nutrients through their roots, they evolved a method by which nutrients could be absorbed from the environment. As such, regular, commercially avilable potting soils which contain high concentrations of nutrients will severely burn the roots of most CPs, causing a quick death. The growing medium of choice is usually a mixture of peat moss and sand.