A dual flush refill device refills a bowl of a siphonic toilet with adequate supply of refill water in response to either a full or partial flush without wasting the refill water. The device provides a relatively high flow rate of refill water from a refill tube to an overflow tube in response to a partial flush, and a relatively low rate of refill water from the refill tube to the overflow tube in response to a full flush. As a result, the toilet bowl is refilled with a substantially similar volume of refill water regardless of which flush option is selected.