In this video, This Old House plumbing and heating contractor Richard Trethewey shows how to save water without replacing the toilet.
1. Close the water shut-off valve located behind the toilet.
2. Remove the cover from the toilet tank.
3. Slide the new flush valve over the vertical overflow tube inside the toilet.
4. Remove the existing flush lever from the toilet tank.
5. Disassemble the pushbutton actuator and fasten it to the toilet tank.
6. Reconnect the dual-flush mechanism to the back of the actuator.
7. Tighten the cable tie to secure the new flush valve to the overflow tube.
8. Open the shut-off valve to fill the toilet with water. Flush the toilet and check the water level.
9. Close water shut-off valve behind the toilet, then flush the toilet.
10. Remove the old fill valve by loosening the nut located on the underside of the toilet tank.
11. Install a new fill valve.
12. Open the shut-off valve and fill the toilet tank with water. Flush the toilet and check the water level. If necessary, adjust the new fill valve for optimum performance.