Filtration: Each cartridge can alkalise and filter up to 300 liters of water. For optimal performance replace filter every 2 months. Includes digital indicator to remind you when to replace the cartridge. ANTIOXIDANTS: The Enviro Products Alkaline Pitcher Filter adds negative hydroxyl ions, which lowers the ORP (oxidative reduction potential) giving the water molecules a negative charge. Water from the Enviro Products Alkaline Filter Pitcher has an ORP ranging from -200 to -400. ORP measures the level of antioxidants in water (the lower the number, the better). ALKALINE: The Enviro Products Alkaline Pitcher Filter raises pH to 8.5 - 9.5 by adding the perfect balance of naturally ionized magnesium, potassium, calcium, and sodium.