A beverage filter or treatment bottle system has a bottle, lid, and a beverage improvement component such as a filter element. A filter element may be positioned to separate the interior space of the bottle into a filtered beverage compartment and an unfiltered beverage compartment. A tube passes through the filter into fluid communication with the filtered beverage compartment. The tube extends through the unfiltered beverage compartment to a nozzle in the lid of the bottle. A lid cover is fastenable onto the lid to enclose and close the nozzle. A filter cartridge may be provided. A UV sterilizer may be provided. An air bypass may be provided.