0.5-micron carbon block replacement cartridge for the EVO X2 Dual Stage Premium RV Water Filter Kit. Second-stage fine filtration that reduces cysts (cryptosporidium, giardia) and chlorine by up to 99%. Also fits most standard 2.5" x 10" canister-style housings. Tool-free replacement. Single cartridge.
The Camco 40638 is the 0.5-micron carbon block replacement cartridge for the EVO X2 Dual Stage Premium RV Water Filter Kit (40639). In the two-stage EVO X2 system, the 40638 serves as the second and final stage of filtration — after the first-stage 40637 sediment cartridge captures larger particles, the 40638 carbon block targets the finer contaminants: cysts like cryptosporidium and giardia lamblia, chlorine, and residual sediment down to 0.5 microns.
At 0.5 microns, the carbon block filtration is significantly finer than the 5-micron 40621 KDF/GAC cartridge used in the standard EVO Premium housing — making the 40638 the right choice when dealing with water sources where cyst contamination is a concern or where the highest level of sediment and chlorine removal is the priority. Beyond the EVO X2 kit, the 40638 also fits most standard 2.5" x 10" canister-style filter housings, making it useful as a standalone fine filtration upgrade in a variety of water filter systems.
The EVO X2 (40639) is a two-canister inline filter system. Each canister holds a separate cartridge: Stage 1 — 40637 (5-micron sediment): Captures larger particles, sediment, and debris. Protects the carbon block cartridge from premature loading. Stage 2 — 40638 (0.5-micron carbon block): Fine-pore carbon block removes cysts, chlorine, and fine sediment that passed through the first stage. Both cartridges require periodic replacement. Replace the 40637 sediment cartridge more frequently than the 40638 carbon block to extend the carbon block's service life.
• 1x Camco 40638 0.5-Micron Carbon Block Replacement Cartridge EVO X2 System Components: • 40639 — EVO X2 Dual Stage Filter Kit (housing + both initial cartridges) • 40637 — EVO X2 5-Micron Sediment Replacement Cartridge (Stage 1) Standard EVO Premium System: • 40621 — EVO Premium KDF/GAC Cartridge (for #40631 housing)
The 40638 is designed for the EVO X2 housing (40639) and standard 2.5" x 10" canisters. It is not the replacement cartridge for the standard EVO Premium inline filter (#40631) — that system uses the 40621 KDF/GAC cartridge instead. If you're unsure which filter housing you have, check the part number on the housing label before ordering.
The 40621 is the right choice for most EVO Premium owners replacing a single cartridge. The 40637 + 40638 combination (EVO X2 system) provides more thorough filtration at two stages — ideal when water quality at campgrounds is a concern or when cyst contamination is possible.