How to Fix a Toilet That Flushes Twice

Why a toilet flushes twice

A toilet that flushes twice usually means water is still flowing into the bowl after the flush cycle should have ended. The two most common causes are a flapper that does not seat properly and a tank water level that is too high. Both are easy to check and fix without special tools.

The flapper is the rubber or silicone part that lifts when you push the handle and then drops back down to seal the flush valve. If the chain is too tight, the flapper cannot close completely. If the flapper is old or warped, it may not seal even when the chain is fine. Either way, water keeps leaking into the bowl, and the tank refills, which can trigger a second flush.

The tank water level matters too. If the water level is set too high, it can overflow into the overflow tube, which sends water continuously into the bowl. That keeps the fill valve cycling and can cause a double flush.

An older toilet may also double flush simply because it does not have enough flush power, a performance issue that the EPA notes was common with some low-flow models from the 1990s. If your toilet is from that era and has no visible problem, a newer model will likely fix the issue.

Diagnose the problem before you adjust

Start by removing the tank lid and watching what happens during and after a flush. You are looking for three things: how the flapper moves, whether the chain has slack or is taut, and where the water stops filling.

If the flapper lifts and then drops too slowly, or if it bounces and reopens, you may need to adjust the chain length or replace the flapper. If the water level rises above the overflow tube, you need to lower the fill valve. If the flapper looks cracked, discolored, or misshapen, replace it.

To check for a slow leak, put a few drops of food coloring in the tank and wait 15 minutes. If color appears in the bowl without flushing, the flapper or flush valve seal is leaking. EPA's WaterSense program specifically points to worn flappers as the most common source of toilet leaks, and calls them an inexpensive part that is quick and easy to replace.

Adjust the flapper chain

The flapper chain connects the flush handle to the flapper. When you push the handle, the chain lifts the flapper. When the tank empties, the flapper should drop back into place and create a watertight seal.

If the chain has no slack, the flapper stays slightly raised and water continues to flow into the bowl. The fix is simple: unhook the chain from the flapper, move the hook to a hole that gives about half an inch of slack, and reattach it. The chain should be loose enough to allow a full seal but not so loose that it gets caught under the flapper.

If the chain is too long and gets tangled under the flapper, it can also prevent a proper seal. Trim the excess link or reposition the hook so the chain hangs straight down without touching the flapper.

For a more detailed walkthrough, see our guide on how to adjust the flapper chain.

If you have a flush tower instead of a flapper, the adjustment is similar but the mechanism is different. Learn more about flapper vs tower flush valve differences.

Set the tank water level

The water level in the tank should be about an inch below the top of the overflow tube. If it is higher, water flows into the overflow tube and down into the bowl, which keeps the fill valve cycling and can cause a double flush.

Most fill valves have an adjustment screw or a float that you can turn. On a float cup valve, pinch the spring clip and slide the float cup down to lower the water level. On a ball float valve, bend the float arm down slightly. On a pressure-sensing valve, turn the adjustment screw counterclockwise to lower the level.

After each adjustment, flush and watch where the water stops. Repeat until the water stops about an inch below the overflow tube. Also check that the refill tube is clipped to the overflow tube and not dangling into the tank; if it is submerged, it can siphon water into the bowl.

If you are not sure what type of fill valve you have, read our guide on toilet tank water level adjustment.

A low water level can also cause a weak flush, so do not lower it too much. See how to fix a toilet not flushing fully if the flush is weak.

Replace a worn flapper

If the flapper is cracked, warped, or simply old, replacing it is the best fix. EPA's WaterSense program notes that old or worn flappers are the most common cause of toilet leaks and that replacement is quick and easy.

To replace a flapper, turn off the water supply and flush to empty the tank. Disconnect the old flapper from the overflow tube ears and unhook the chain. Take the old flapper to a hardware store to match the size and shape, or look up your toilet model number. Attach the new flapper, connect the chain with a little slack, and turn the water back on.

A flapper is usually a universal part, but some toilets use a special design. If you are unsure, check the manufacturer's spec page or the model number inside the tank.

For a step-by-step walkthrough, see how to replace a toilet flapper. If the flapper is not the issue, see toilet flapper won't seal for other causes.

If your toilet has a flush tower instead of a flapper, the replacement process is different. See how to replace a toilet flush tower.

When the fix is not enough

If you have adjusted the chain, set the water level, and replaced the flapper, but the toilet still flushes twice, the problem may be the flush valve seat or the toilet design itself. Older low-flow toilets from the 1990s were sometimes associated with double flushing, a performance issue that EPA notes was part of the reason WaterSense added performance criteria to its specification.

In that case, consider replacing the toilet. Modern toilets use no more than 1.28 gallons per flush and are independently certified to clear waste effectively, so you do not have to choose between water efficiency and a single flush.

Before buying, check the toilet's rough-in size and bowl shape to make sure it fits your space. Our guide on how to measure rough-in can help.

If you prefer a simple, reliable single flush, look at our best single flush toilets.

If you want to save even more water, consider a dual flush toilet, which uses a smaller flush for liquid waste and a full flush for solid waste.

What to pick for your situation

Questions

Is a toilet flushing twice a sign of a leak?

Not always, but it can be. If the flapper does not seal completely, water trickles into the bowl and the tank slowly refills. That is a leak even if you do not see water running. EPA's WaterSense program identifies worn flappers as the most common source of toilet leaks. A food coloring test can confirm whether you have a leak.

What tools do I need to fix a double flushing toilet?

You usually need no tools at all. Adjusting the flapper chain or the fill valve is done by hand. To replace a flapper, you may want a pair of pliers to disconnect the chain hook. A sponge and a towel help clean up any water that spills when you remove the flapper.

Can I fix a double flush by just lowering the water level?

Sometimes. If the water level is above the overflow tube, lowering it stops the constant refill cycle. But if the flapper is worn or the chain is too tight, lowering the water level by itself will not stop the double flush. You need to address the specific cause.

How often should I replace the flapper?

Flappers are inexpensive parts that wear out over time. EPA notes that most toilet leaks are due to old or worn flappers. If your flapper looks cracked, feels stiff, or no longer seals after many years of use, replace it. A five to seven year lifespan is common, but hard water or cleaning chemicals can shorten it.

My toilet still flushes twice after I fixed the flapper and water level. What now?

Check the flush valve seat for mineral buildup or damage. You can clean it with a soft brush. If the seat is scarred, you may need to replace the flush valve. If the toilet is an older low-flow model, the double flush may be a performance limitation of the design itself. In that case, upgrading to a newer WaterSense labeled toilet is the most reliable fix.