An insert may be used with a container that includes a lid with a suction opening and a liquid storage portion where the lid threads onto the liquid storage portion to allow liquid from the liquid storage portion to be consumed through the suction opening by a user. The insert includes a barrier with an outer perimeter that is configured to be captured, and form a seal against liquid, between the lid and the liquid storage portion when the lid is threaded onto the liquid storage portion; a first one-way valve through the barrier and configured to allow the liquid to flow from the liquid storage portion to the suction opening during consumption of the liquid by the user; and a second one-way valve configured to allow air to flow into the liquid storage portion.