An electrodeionization apparatus comprising an endblock formed from a resilient material, and method for making the same. The resilient material may include various types of thermoplastic elastomers, such as, styrene block copolymers, copolyesters, plolyurethanes, polyamides, thermoplastic elastomeric olefins, and thermoplastic vulcanizates. The resilient material may have a Shore A hardness of between about 40 and about 90.