How to Fix a Toilet That Flushes Twice

How to Fix a Toilet That Flushes Twice

A toilet that flushes twice — where you hear a second flush cycle shortly after the first — wastes water with every use. It's almost always caused by the flapper staying open too long or the water level being set too high. Both are easy fixes.

Why Toilets Double Flush

A double flush happens when too much water leaves the tank during a single flush. The bowl fills, drains, and then the remaining water in the bowl triggers a second siphon action — causing a second flush cycle.

The two most common causes:

• Flapper stays open too long — too much water enters the bowl before the flapper closes
• Water level too high — excess water in the tank means more water enters the bowl than needed

Fix 1: Adjust the Flapper (Most Common Fix)

The flapper controls how long water flows from the tank into the bowl. If it stays open too long, too much water enters and causes a double flush.

Option A: Shorten the chain
A chain that's too long can keep the flapper partially open longer than needed. Try shortening the chain by one or two links — this causes the flapper to close sooner.

Option B: Replace with an adjustable flapper
Some flappers have an adjustable float that controls how long they stay open. Replace your current flapper with an adjustable one and dial it down to reduce water flow.

Option C: Replace with a standard flapper
If your current flapper is warped or deteriorated, it may not be closing at the right speed. Replace it with a universal toilet flapper.

Fix 2: Lower the Water Level

If the water level in the tank is too high, too much water enters the bowl during each flush — causing a double flush.

1. Remove the tank lid and check the water level — it should be 1 inch below the top of the overflow tube
2. If it's higher, adjust the fill valve float downward:
   • Cup float: Pinch the clip and slide the float down the fill valve shaft
   • Ball float: Bend the float arm downward slightly
3. Flush and check — the double flush should stop once the water level is correct

Fix 3: Replace the Fill Valve

If adjusting the float doesn't hold the correct water level, the fill valve may be faulty:

👉 Fill valve and flapper repair kit — replace both for a complete fix

Bottom Line

A double-flushing toilet is almost always fixed by shortening the flapper chain, replacing the flapper, or lowering the water level. Start with the chain adjustment — it takes 30 seconds. If that doesn't work, lower the water level. Both fixes stop the water waste immediately.