Ceramic Water Filter Cartridges. Biopure has available two brands of ceramic filter cartridges all made in the UK. The doulton ceramic filters and the Ultraceram Coldstream ceramic filters are absolute rated for the worlds finest filter cartridges. Choose from the doulton ultracarb, doulton sterasyl and doulton super sterasyl or Ultraceram coldstream ceramic carbon filters. Our ceramic filters are cleanable giving you a longer lifespan from your cartridge.