Water blocks may be disassembled for cleaning purposed on an occasional basis. Your warranty is not voided on dis-assembly of the water block, but the customer loses the EK leak-free guarantee which comes with a factory tested water block.
EK Water Blocks recommended steps to be taken in order to prevent any biological growth within the warm waters of your computer liquid cooling loop.
Plasticizers or dispersants are additives that increase the plasticity or fluidity of a plastic, especially polyvinyl chloride (PVC) tubing in computer liquid cooling.
Copper does not react with water, but it slowly reacts with atmospheric oxygen, forming a layer of brown-black copper oxide.