These Kleenwater brand water filters offer both very high quality and exceptional value. Proper maintenance is imperative to keep your reverse osmosis system operating efficiently. It is important to change the sediment filter cartridge routinely so there is no significant pressure loss. High feed line pressure is critical and a pressure reduction would drastically reduce the reverse osmosis membrane performance. As the KW2510G 5 micron sediment filter gets impacted with dirt, rust and sediment it can become restrictive and needs to be replaced. The KW117 and the KW2510CB are carbon filters that function to remove chemicals and chlorine. It is vital to remove chlorine from the water before it is fed to the reverse osmosis membrane. This membrane is made of thin film composite material that is damaged by the presence of chlorine. The reverse osmosis membrane should be changed every 3 years. Our membrane is constructed of thin film composite material which is efficient and is able to remove dissolved solid mineral such as sodium, nitrate and fluoride. The thin film composite membrane material is made in the USA. Our KW2551 in-line post filter is comprised of 50% granular activated carbon and 50% calcium carbonate. The carbon will further remove impurities that impact taste. The calcium carbonate will replenish the water with a small amount of healthful alkaline mineral for pH balance and to give the water great taste. Final note - it is recommended the water storage tank be sanitized routinely. For optimum performance the empty tank should have approximately 5 psi of pressure. A schrader valve is built into the tank to facilitate tank pre-charge. These tanks are susceptible to becoming water logged. If the permeate flow from the reverse osmosis faucet is slow yet the tank feels heavy air is likely required. It is the air pre-charge that provides the potential energy required to dispense the water.