Step 3 · Adjust the Float Cup

To lower the water level, you must adjust the float cup downwards. Look for the adjustment mechanism on the fill valve. Most modern float cups have one of two adjustment types. The first is a long plastic adjustment screw that runs parallel to the fill valve; use a screwdriver or your fingers to turn this screw. Turning it counter-clockwise typically lowers the float. The second type is a spring-loaded clip; you'll need to squeeze the clip and then manually slide the entire float cup down the fill valve shaft. Lower the float by about a half-inch to start.