Toilet Double Flush Repair Guide

A toilet that flushes twice can be pretty inconvenient. It’s not just an annoyance, it has negative environmental and financial effects, too.

The water wasted during that second flush will really increase your water bill at the end of the month.

The double flush is thankfully a quick and easy fix, and we’ve got a great guide to help you through it.

The Flushing Process

Before we dive into the details, let’s start by talking about how a toilet normally flushes.

Most homes today have gravity-fed toilets, which are made of two basic porcelain parts; the tank and the bowl. Flushing might seem like it’s all-bowl, but most of the process actually goes on in the tank.

The drainhole at the bottom of the bowl collects the waste until you’re ready to flush. There’s a syphon mechanism at the bottom of the bowl that creates a vacuum when you turn the handle, allowing water from the tank to flow in at high pressure through the flapper, sending the waste down the drain.

The parts that make up these processes, as well as the special valve in the water tank that measures how much water the tank holds, are crucial to the flush.

A problem with any of these parts will cause an issue like a double flush.

Identifying the Cause

The likeliest suspects for your double flush are; 

  • A problem with the flapper 
  • A problem with the water level in your tank. 

Let’s tackle the flapper possibility first.

Reason #1 – Failing Flappers

Located inside the tank, the flapper controls the release of water from tank to bowl. It could either need adjusting or replacing, so let’s assess the situation. We have plenty of guidance and advice, you and your toilet are in good hands!

Removing the Flapper

Remove your flapper by first unclipping the chain, then pull the flapper out from under the two pegs. Next, attach the chain of the flapper to the flush lever, making sure that it’s going up and down as far as possible with minimal slack. Note that if there is too much slack, or if the chain is too tight, it might not be performing optimally and need replacing.

Be mindful of the position of your flapper chain – if it’s too low on the chain, too much water enters the flapper and this can result in a double flush. The video below demonstrates how to correctly check whether the float is correctly positioned on the flapper, and how to adjust it accordingly: 

Finally, turn on the water supply valve and wait until the tank fills up. Pull the lever to perform a flush test and check if everything is working properly once more.

Fixing a Non-Adjustable Flapper

If your flapper is not adjustable, you may have the incorrect flapper installed. Don’t worry, this issue is also pretty simple to resolve – all you need to do is grab a new flapper at your nearest home-improvement store. Not to fret, we have a guide for flapper replacement too!

To ensure the correct fit, take your old flapper with you to the store when buying your new one. Korky is our recommendation if you’re looking for a reliable brand, but there are plenty out there.

Weak Flapper

A potential solution is replacing your bowl flapper with a heavier one. A lightweight flapper wears and tears, soon becoming too weak to hold water back the way it’s meant to. This can lead to your flapper staying open longer than usual, letting too much water through. If your toilet keeps acting up after trying these fixes, your other possibility is an overfilled tank.

Reason #2 – Too Much Water in the Tank

 If your tank is filling up too quickly after flushing, extra water will continue to flow and trigger a second flush. There are a couple of reasons why your tank is overfilling, but we’re probably looking at a fill valve or a float cup, which are closely connected. 

Your valve could either be The fill valve is responsible for controlling the refill in a tank, and it’s an easy adjustment if incorrect setting is the problem.

Adjusting and Replacing the Valve

Adjust and tighten the screw on the top of the fill valve to lower the arm. If you can’t find the screw, your fill valve may be too old and instead of replacing the screws, you might want to replace the whole valve with a newer model.

Check out another of our helpful articles for a detailed step-by-step on how to replace your valve. You can’t go wrong with a good-quality Fluidmaster or Korky flapper, available at most hardware stores.

This video shows you how to replace the fill valve, but you might need to turn up your brightness and listen to it a few times – the dramatic double-flush music makes it hard to hear some bits. 

Adjusting and Replacing the Float Cup

Your toilet valve can either be ball-and-arm or cylinder floats. If you have a valve, check for any damage to the entire mechanism, including the ball and screws.

If your toilet has a cylinder float, you’re looking for the important clip attached to a small tube attached to your toilet’s valve.

If all your cylinder needs is an adjustment, go ahead and raise or lower the clip accordingly. 

This video is a great, clear, easy how-to on adjusting a cylinder float!

The video below is a clear visual demonstration of a float adjustment, although it’s not in English. It shows a toilet which needs a higher water level, while most videos look at lowering the level.

Some tanks may even have a fill line inside the tank to indicate the correct level. 

If your float is damaged or worn, it needs replacing. We have a great guide on how to adjust or replace your float cup, make sure to check it out!

Once you’ve adjusted or replaced the issue, your tank should return to a lower level of water and your toilet will no longer flush twice. If you’re still dealing with a double flush disaster, it’s time to call a plumber. 

Final Thoughts

Fixing a double flusher is an easy and necessary process, saving your wallet and the environment. Following our instructions will resolve your flushing issue quickly and easily, solving your problem solo and successfully. Happy flushing!

 Pro Tip:   When buying a flapper, remember that your best bet is a heavy, sturdy choice!