The toilet water tank refilling system includes an inlet pipe adapted for installation within the toilet water tank and adapted for connection to a water supply, a valve connected to the pipe, a float operably connected to the valve to open the valve when the water level falls below a predetermined level and to close the valve when the water level in the tank reaches the predetermined level, and a valve outlet discharging water from the water supply into the tank when the valve is open. The system does not have a valve outlet discharging water from the water supply through the overflow tube directly into the toilet bowl. The only paths for discharging water from the water supply to the toilet bowl in the toilet water tank refilling system are through the tank's flush valve when the toilet is flushed and through the overflow tube when the water level in the tank exceeds the predetermined level.