Step 6 · Adjust Water Level and Test Flush

This is the step people usually slow down on. Go finger-tight first, then a quarter turn. No rush — replay the clip whenever it helps.

The final step is to adjust the water level and test the flush. Let the tank fill completely. The water should stop filling when the level is about 1/2 to 1 inch below the top of the overflow pipe. If the water is too high or too low, adjust the float on the fill valve. For float-cup style valves, this is usually done by turning an adjustment screw or squeezing a spring clip and sliding the float up or down the fill valve shaft. Refer to your specific model's instructions. Once the water level is set, flush the toilet. Watch to ensure the flapper lifts correctly, stays up long enough for a full flush, and then seals completely. Check that the chain doesn't get tangled or caught. Flush a few more times to confirm everything is working smoothly and there are no leaks.