To avoid the black discolorations or natural build up from occurring, please keep the bottles clean & dry between reuses. Do not store beverages overnight in bottle. Always store with straw, lid, and body disassembled and separated to allow parts to remain completely dry and free of visible moisture to prevent discoloration.
To effectively clean your water bottle, we recommend that you disassemble and soak the parts in hot mild soapy water, then scrub parts using nylon or plastic cleaning pads & bristle brushes (e.g., Scotch-Brite™ Dobie® All Purpose Cleaning Pad). Rinse. Shake off residual water after rinsing or removal from dishwasher, then allow to completely dry overnight until visibly dry before reassembly and reuse.