TasteThe Sawyer filter removes taste that comes from bacteria, dirt, and green matter.ChemicalsThe Sawyer filter does NOT remove iron, sulfur, other chemicals, or simple compounds. Taste can be masked by using flavor additives like Gatorade or crystal light (filter needs to be cleaned immediately after using them).Heavy MetalsThe Sawyer filters are not made with charcoal. While other portable filters have charcoal, they lack in amount of media and adequate dwell time. Therefore, they only remove small amounts of heavy metals, pesticides, etc. (when used in real life applications). Try using better sources of water, if possible.