Replacement purifier cartridges for GeoPress are designed to last up to 350 cycles (65 gal. / 250L). Lifespan will decline when filtering and purifying water with high levels of silt, sediment or tannins. Cartridge press time increases towards the end of the cartridge lifespan; when press time reaches 25-30 seconds, cartridge should be replaced. Cartridge continues to protect, even as press time increases. Compatible with One-Way Silicone Valve for electrolytes and drink-mixes. GeoPress® cartridge and one-way valve ships pre-installed in every GeoPress Bottle.