At Dowler Homestore we stock the Bobble water bottle. The Bobble filter has a active carbon filter that gives water a slight positive electrical charge This removes chemicals and impurities in the water. As the water flows through the positively charged carbon surface, the negative ions in the impurities stick to the carbon particles. Carbon filters need little maintenance and are also known to be one the most absorbent materials. Bobble's filter removes organic impurities from tap water and surpasses the NSF International Standard 42 for chlorine, flavour and reducing odours. For best results we recommend replacing the filter after 2 months or 150 litres The filters are only to be used in Bobble water bottles. Caution: Not to be used with water than is microbiologically unsafe or of unknown quality.