Ultrastream is designed to last a family of 4 each drinking 2 liters (2+ quarts) of water a day a complete year.
Like all water purification systems, it largely depends on the "quality" of the source water. If the water is very hard, then it may not last as long.
To get all your questions answered, visit: https://www.alkawayusa.com/about-ultrastream#about-ultrastream
To order a Replacement Cartridge visit: https://www.alkawayusa.com/shop#replacement-cartridges