Considering Cutting the Overflow Tube Below the C-L Marking on the Fill Valve? Author: Paul Bergstrom Last Update: Jun 08, 2006

Cut the overflow tube only after you check that the water level you need (either as permanently marked inside the tank or what you determine is required) is at least 1/3 inch below the height that you intend to cut the overflow tube. In addition, it is good practice to test and verify that this water level provides adequate water for flushing the toilet and refilling the bowl.NOTE: Some toilets produced before anti-siphon standards became common (and others in which replacement flush valves have been installed) have overflow tubes taller than necessary. These can be cut with no negative impact on the toilet's performance. The shorter height will give added protection from flooding if the fill valve fails.