Some pollutants, like halomethanes, can evaporate and recondense along with water, sometimes becoming more concentrated in the finished water than in the raw water. Because distilled water is devoid of dissolved oxygen, it tastes flat. A filter is something that has holes in which to permit particles of a certain size to pass through, while blocking passage of a larger size. Examples of filters are paper, charcoal, and window screens. Activated carbon filters are inexpensive, so they are fairly popular.
Charcoal filters are able to block the passage of sediment and suspended solids.
They also absorb some gases, like chlorine and halomethanes. They do not remove dissolved solids, especially toxic materials. Although carbon filters do absorb some substances like chlorine and halomethanes, they can also become saturated and begin releasing these substances back into the water. It does an excellent job in reducing harmful pollutants. Reverse osmosis enhances the oxygen content of water, giving it a fresh and lively taste.