Water-saving siphonic toilet and equalization system therefor

A siphonic flush toilet including a toilet bowl, a pressurized trapway for carrying the contents of the bowl to a drain during flushing, a tank, a flush valve, and a water supply in the tank that flows water into the bowl on each flushing, the trapway including upper and lower traps, comprising a timed pressure equalization system, the system comprising:

• a. A source of pressurized air in the tank and coupled to the trapway to establish a positive air pressure, above atmospheric pressure, in the trapway prior to flushing, wherein the lower trap remains closed prior to flushing to maintain positive air pressure between the upper and lower traps prior to flushing;
• and
• b. An equalization member having a first end and a second end, and a body portion there-between, the equalization member coupled to the source of pressurized air and the trapway, the equalization member having a reservoir for holding a defined quantity of water and a restricted opening at the second end, the restricted opening in fluid communication with the water reservoir, the equalization member for timing and regulating the transition from negative to positive pressure after the siphon breaks to reduce the loss of residual water used to refill the pan from a fixed cavity within the bowl, wherein the reservoir and restricted opening are sized to permit a volume of water to completely drain from the reservoir and permit air to enter the equalization member after a pre-determined time period during a flush.