If you have toilet flush problems, they are hard to ignore and need to be addressed as soon as possible. If they are left, they will only get worse, and no one wants to be without a working toilet.
Thankfully, regardless of the type of toilet you have, toilet flush issues can be fixed on a DIY basis. Even the more complicated issues, such as a broken flush valve, can be replaced by a competent DIYer. And the new parts are not expensive.
Here, you'll find what you need to know to resolve any annoying flush issues.
Jamie is a highly experienced manager with over 24 years of expertise in the Plumbing & Heating sector, having worked for both national and regional merchants. He now brings his knowledge to Build & Plumb, an online retailer, supplying top-quality products for DIYers, renovators, and trade professionals alike.
Common toilet flush problems
There are many reasons you may be experiencing toilet flush problems. Still, some problems are more common than others, as Jamie Heath, plumbing & heating expert from Build & Plumb, reveals, “The most common toilet flush problems typically involve a broken flush button or the cistern not filling.”
He continues, “A broken flush handle or button can be caused by multiple issues, one being that the button is getting stuck due to a buildup of dirt and debris.” But this isn’t the only reason, explains Heath. “It can also be caused by the connection between the button and flush valve being disengaged.” He adds, “More simply, it could just be a faulty button or mechanism due to wear and tear over time.”
Alongside a broken flush button, another common problem is low water levels, shares Heath, “Low water levels in your cistern can be a main cause of toilet flush problems, as a toilet needs a full tank of water to create enough force to empty the toilet bowl.” He adds, “When the water level is too low, it doesn’t provide enough water, often resulting in a weak flush. Water levels can typically be too low due to a problem with the fill valve and float mechanism”.
Try these to help fix toilet flush problems
This unit is ideal for toilets with a 2-inch outlet and a 1/2-inch inlet (both common sizes). In addition, it features both full- and partial-flush options, as well as a cable-connected flush button.
Scale can cause toilet-flush issues, especially in hard-water areas. This multi-purpose descaler boasts a powerful formula that cuts through tough limescale. Suitable for use on plastic.
Fill problems can be caused by a faulty inlet valve. This easy-to-install valve is a quiet, slow-filling valve that ensures your cistern fills to the correct level, thanks to its tank and bowl water-level adjustment dials.
Other reasons for toilet flush problems
Toilet flush problems are not exclusive to broken flush handles and low water levels. There are other issues that can be the cause, as Heath shares, “A constant flow of running water from the toilet tank is a fairly common problem that is typically caused by a faulty fill valve.”
He adds, “A fill valve is responsible for refilling the water tank after you flush the toilet; however, if it becomes faulty, clogged, or misaligned, water can continue to flow into the tank.” If you are having this issue, he says, “It’s important to replace your fill valve as soon as possible to prevent wasting large amounts of water and increasing your water bill”.
Another issue is worn, damaged, or clogged flush valve seals. Heath explains, “These valves create a tight shut-off at the bottom of the cistern to prevent water from leaking into the toilet bowl. Therefore, when they are damaged or clogged, they won’t seal properly, resulting in low water levels in the cistern and a weak flush”.
If you live in a hard-water area, scale can be an issue, explains Laurence Barwick-Smith, a wastewater and drainage specialist at KEE: “A buildup of limescale can cause a toilet float to stick, which can affect how the toilet flushes.” He adds, “If this is happening, you need to clean the float and fill valve with an acidic cleaner like white vinegar or a descaler. If the problem persists after cleaning, you may need to replace the float mechanism.”
Laurence Barwick-Smith is a wastewater and drainage specialist at KEE, where he has worked for over 10 years. He is committed to offering professional advice and finding solutions to avoid expensive damage, and sharing this knowledge.
How to fix toilet flush issues
Different toilet flush problems require different solutions. Fortunately, most of these can be fixed by yourself. Here, we look at some simple solutions to resolve any flushing issues.
Flush mechanism
If the flush handle/button feels loose, it's simple to sort. Barwick-Smith says, “You should tighten the nut that holds this in place.” He adds, "However, if you have a chain, this should only be tight enough so that there is a small amount of slack when the handle is not in use, as too much slack can prevent the flapper from lifting fully.”
Another issue could be that it needs a clean, says Heath, “It could be that the button is getting stuck due to a buildup of dirt and debris. If this is the case, you must isolate your water supply, remove the button and clean it using a soft cloth.”
Faulty fill valve
A common issue is a hissing noise. Barwick-Smith explains why, “A hissing noise coming from the toilet can suggest that it is the fill valve causing flushing issues. Check that the valve is fully open and not clogged with debris or scale.” He adds, “The valve can be cleaned, but they are usually inexpensive to replace completely."
Low water level
If the water level is low, the first step is to remove the cistern lid and check the level. Barwick-Smith says, “Ideally, it should be a centimetre or two below the top of the overflow tube. He adds, "If it is too low, adjust the water level using the float mechanism."
Heath explains how to do this: “Take a flat head screwdriver and turn the screw anti-clockwise to raise the water level or clockwise to lower the water level.” To finish, he adds, “Then with the lid still off, flush your toilet and see if the water level rises; it should be around an inch below the top of the overflow tube.”
Blockage
If you have a minor blockage, you can use a plunger. Barwick-Smith says, “Ensure that there is enough water in the toilet bowl to cover the head of the plunger, and create a seal around the opening of the drain before plunging vigorously.”
If a plunger doesn’t sort out the issue, you may have a larger blockage. Barwick-Smith adds, “Larger clogs may require the use of a toilet auger to break up and remove the blockage.” Check our what is a drain snake guide for more on this.
How to replace a flush valve unit
Replacing a flush valve is something a DIYer can tackle, but there are a few steps to follow to ensure you don’t flood your bathroom. Jamie Heath runs through the initial step. “When replacing a flush valve, it’s crucial to start by isolating the water supply to the cistern.”
He adds, “Once the water supply has been isolated, you must flush the toilet to empty it. If the cistern doesn’t refill after flushing, then the water has successfully been isolated."
The next step is to remove the tank/cistern. Heath says, “Remove the toilet tank so you can access the old flush valve. Once you have access to the old flush valve, you can remove it and install a new flush valve.”
But he adds a note of caution, “It’s important to note that this process isn’t the same for all types of toilets and their specific flush mechanisms.” He continues, “Flush valves can differ depending on whether you have a single or dual flush, so you must ensure that your new flush valve is suitable for your toilet.”
If unsure about anything, consult a professional. Alternatively, a simple option is to take a pic of the unit and go to your local hardware store for advice on a like-for-like replacement.
Replacing an inlet valve
An inlet valve is connected to the water supply and fills the cistern. But if it's not working you can just replace this part rather than the flush valve unit. Heath explains, “Replacing a toilet inlet valve, also known as a fill valve, is typically considered to be easier than replacing a flush valve unit.”
He adds, “This is because inlet valve replacements don’t require the removal of the entire toilet tank. However, you will still need to isolate the water supply and empty the cistern before replacing an inlet valve.”
If you can’t fix your toilet flush issues, it might be time to replace your old toilet with a new one. Check out our toilet dimensions guide to ensure you get the right size and new toilet costs to see how much to budget. If you're planning a full toilet renovation, our small downstairs bathroom ideas will offer inspiration.
