Dual Flush Toilet Problems

Dual Flush Toilet Problems

Even the best dual flush toilets have hiccups once in a while. They are very efficient toilets but like everything man-made, they have a couple of things here and there that always seem to come through the cracks even in a well-designed product. Dual flush toilets have a similar design to that of a regular single flush toilet with the difference being that you have two buttons as an extra option instead of the one option on a standard design.

These toilets are designed to maximize water conservation as best as a gravity-assisted toilet can. They are still gravity toilets just with an added flushing option. We all know the situation with water in some parts of the world is dire and needs very swift solutions. For every 1 liter that a privileged person throws away, a less privileged person loses 5. This is because of how inefficient the waterworks are in poorer countries, and so if you know any people that are in a water crisis, think of getting them a dual flush toilet. It’ll also come in handy for you if your water bill is getting out of hand; it can cut your water expenses by 40%, now that’s something that might help out a few people.

How Does a Dual Flush Toilet Work?

The best dual flush toilets can save up to 40% of the net water usage per household per month. So the premise behind this is the double or single flush options for flushing. The top of the tank has two buttons that stand for different flushes; the smaller button is for the liquid waste only flush which uses half the amount of water as a normal flush would, and the bigger button is for the standard flush which is the water killer.

A single flush uses about 3 liters of water as opposed to the normal 6 liters of a standard flush. A single flush might not have the same strength to flush down solid waste but is very effective for other smaller flushing needs. However, with that being said there are times where it is possible to flush solid waste with a 3-liter flush and ongoing investigations and research are striving to design a gravity-fed system that is capable of using 3 liters or less for a regular flush.

The tank inside a dual flush toilet has two valves connected into one that allows for the regulation of volume control. When one button is pushed, only one valve is triggered allowing only 3 liters of water to flow out. When the full flush button is activated then both valves are triggered allowing all of the water in the tank to flow in the bowl for a more forceful flush. The trapway at the bottom of the bowl is made roughly 4-5 inches to allow for easier waste removal than a regular toilet that has a smaller trapway.

Even with a more water-efficient design and easier waste disposal system, there remains a couple of problems that might undo all the good work that the toilet might do, so let’s take a look at some of these instances.

Dual Flush Toilet Problems


What might start to happen after installing a dual flush toilet is that some people, either visitors or friends might come by the house and might not be familiar with this type of toilet and try to flush solid waste with a half flush. This is the prime reason for so many complaints of clogging, and unfortunately, there’s not much that can be done about this unless you take your friends and family through a toilet usage course and explain what the correct procedure is, which might be a little strange.

Dual Flush Toilet Problems Clogging

The drains in a standard household are design smaller to save on space and cost. This means that when a toilet is flushed and the waste goes down the drain without sufficient force to propel the waste out and into the sewer system a blockage might occur. A blockage might not clog up the whole drain all at once, but after a build-up of waste it might end up backlogging the toilet, causing the bowl to overflow and spill all over the bathroom floor.

The one thing that might do the drains the world of good is to double flush them once in a while. Do a double full flush once in a while and maybe the movement of water could dislodge the stuck waste in the drain. Although, this might seem to some as a waste of water.

Water running into the bowl

The valves or the flappers in the cistern might become old and dysfunctional at some point which might cause water to leak out of the tank continuously. When water flows out of the tank continuously the filler valve stays open to keep on filling the tank up to the appropriate level; this results in a perpetual circle of water being wasted. Sometimes it might not even be noticeable unless you look for it. So try to swap out the flapper once in a while and keep a lookout for running water.

The average toilet takes between two and three minutes to refill after flushing, and for these dual flush types the tank can hold 6 liters, so you do the math. A total of 100 liters of water might be getting wasted every hour that the problem is ongoing, so be vigilant.

The problem might not be an old valve or flapper, for instance, if you have just had a new toilet installed and it starts leaking then it could be some debris from dirty water that is holding the flapper open. Otherwise, the problem might be a faulty valve that was sent from the factory in which case turn off the inlet tap on the outside of the cistern and get them to send you a new one.


Any bathroom installation should be well maintained and cleaned regularly to keep it presentable and to prevent problems from developing. It;’s probably a good idea to open up the tank of the toilet once in a while to check the stat of the inside parts, if it is common for your area to suffer from dirty water then you should do it regularly, especially if the water contains a lot of limestone extracts.

The contents of the water will cause the inner parts of the valves and flapper to become weak or to become unsuitable for further use. If this is the case then switch off the inlet house tap and flush the toilet until there is no more water in the tank, then pour boiling water over the internal parts and brush them lightly to remove any residues. After that, turn the tap back on a let the toilet refill.

Another part of the toilet that might develop a problem from unclean water is the ring holes or the rim of the toilet, place a small mirror in the bowl facing up towards the rim and check to see that all the holes are open and maybe just give them a good scrub anyway.


This is not necessarily a problem as such, but it is a slight disadvantage for some who can’t afford the higher price range. The more these toilets are used and increase in popularity the lower the price will become, so you could also choose to wait a while before getting them because they might go down in price. In the long run, you will most likely save way much more money than you paid for it. With the higher conservation of water and the increased efficiency, you’ll end up paying less for your water bills at the end of each month, therefore, saving money.

The other aspect of the price is, of course, the replacement and repairs cost. The parts for a dual flush toilet are more expensive than a standard toilet and in most cases are harder to find than standard parts. The buttons and double valve parts are the most widely needed parts for replacing, and they might usually be located at a standard plumbing store, if not then there should be online options that you can search for; the important thing to check would be that the parts fit the measurements of your toilet at home.

Fill Valve Malfunction

The filling valve might be the problem for continuous running water as mentioned before. The fill valve might fill the tank to the appropriate level but fail to switch itself off, causing the tank to get too full, leaking water out of the overflow pipe that leads directly into the bowl. Maybe the toilet won’t start filling after the flush, in which case the fill valve has probably developed a problem. This doesn’t happen often and if it does it might be due to faulty equipment send from the factory, so if it happens to you then the best course of action is to simply replace the whole valve because if it gives you a problem once and you manage to get it working again, it will most likely bomb out again somewhere down the road.

Buttons Not Working

In our research, we’ve come across a fair number of people who complain about the flush buttons not working. This problem does tend to develop after some time because the buttons work on springs which might get rusty and break or end up falling off. Some versions of the dual flush toilet come with two handles, which don’t last as long, but when they do break, they are a lot easier to fix than the buttons. You might want to try messing around with the buttons to see if you can get them to work which is perfect5ly fine but it will dawn on you at some point that the only way forward is to change them out for new ones.

What To Make Of All This?

It might be a little bit overwhelming to read all of the negative potential problems of the toilet and you’re probably ready to run away without even considering buying one of these toilets ever again, but it’s not that bad. These are possible things that could go wrong, it is mostly worst-case scenario stuff. Any toilet can develop problems and even a top-notch toilet can give you hassles, but for the most part, these problems aren’t very common with the best dual flush toilets.

You will pay more for the toilet itself but in the long run, it will save you a lot of extra money. The water consumption of toilets is crazy and we use so much water in the waste disposal systems which could be used elsewhere, and so with the development of the dual flush system, this problem gets addressed rather well.

Final Thoughts

These key considerations have pointed out the failings of the best dual flush toilets and toilets in general, but there are so many other upsides and benefits to these devices that will have to be covered in another article. So make good use of these pointers and try to look out for potential threats and how to avoid them. It’s better to check frequently on the condition of the toilet than to check once in a while and find that the problem is already too big to be quickly sorted out.

It does take a little more effort but it might save you from those bathroom disasters that everyone truly dreads, and rightly so, trust me I know. So go for it and take the first step to become a water conservationist; it’s a good feeling when you’re protecting a valuable resource and saving your wallet at the same time. Now you know the details of the dual flush toilet, so you can share the information with someone who you know is struggling with constant stress. So, “are these toilets worth it?”, we’ve laid the truth on the table and now the choice is yours.

Mumtahina Adira

Hello World! This is Mumtahina Adira. I am a Home Improvement blog writer.

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