Chemical Purification - adding bleach or iodine to your water. This is a lightweight solution - but is a bit more complicated than boiling. Water must sit after adding chemicals. Cold water should be allowed to sit overnight. If you camp a great deal a filter might be right for you.
Water filters produce the best tasting water.
Only water filters can remove pollutants from water. Filtration devices are the most expensive alternative. Water filters can be a bit bulky to carry. I don't think so. Many recreation facilites offer water that is not potable.