Additive delivery systems and containers

An additive delivery system for use with a portable liquid container configured to hold a base liquid, the system comprising:

• a base liquid container having an inner volume to hold a base liquid, a bottom and a threaded mouth;
• an additive reservoir including at least one wall defining a space holding a liquid additive and an outlet from which the liquid additive exits the additive reservoir;
• a cap assembly configured to threadedly engage with the threaded mouth, the cap assembly having a bottom, a top, a spout at the top of the cap assembly and configured for movement between open and closed positions to control flow of liquid from the spout, an upper component coupled to the additive reservoir, and a lower component including at least one wall that at least partially defines an additive reservoir enclosure in which the additive reservoir is received, the lower component including an opening and configured to permit base liquid from the inner volume to flow into the opening and through the additive reservoir enclosure, and a metering port configured to receive liquid additive from the outlet of the additive reservoir;
• and
• a base liquid flow path extending through the cap assembly to the spout, the base liquid flow path fluidly coupled to receive liquid additive from the metering port at a mixing area to mix the liquid additive with base liquid and including a one-way valve in the base liquid flow path upstream of the mixing area that prevents backflow of base liquid into the base liquid container.