A note regarding feed water for all cartridge systems:
Virtually any type of water, including tap water, can be used as supply water to any deionization system. However, the cartridge use and the cost of operation can be extremely high with tap water as feed water. For example, the typical DI cartridge has a capacity of 1200 grain-gallons. If your feedwater has a hardness of 20 grains, you will only get about 60 gallons of reagent water per cartridge change. In most cases, RO water or distilled water is used as feedwater for DI systems. Using softened water will not decrease cartridge usage, as softening merely replaces Ca++ and Mg++ ions with Na+ ions.
O-rings for PCS deionization cartridges:
D-0803, D-0809, D-0813, D-0820, D-0832, D-0835, D-0836, D-5021, D-5027
LS-0803, LS-0809, LS-0813, LS-0820, LS-0835, LS-0835, LS-0836, LS-5021, LS-5027