Tier one contains natural zeolite ore designed to filter chlorine and other heavy metal impurities. Tier two contains calcium sulphate, which helps absorbs organic compounds, toxic metal ions, chlorine and harmful bacteria and viruses in the water. Tier four contains a PVC non-woven filter layer, designed to filter solids and visible impurities. Get one or two tap faucet water filters. Tier three contains activated Carbon which aim to absorb chlorine, odour, and a variety of toxic and hazardous substances in water. Have instant filtered water from your tap!