How to Fix a Running Toilet: Complete Repair Guide

If you have a running toilet, you already know that it's a bit of a nightmare. It's noisy, the water bill goes up, and it's one of those household issues that starts as a mild annoyance and quickly becomes impossible to ignore. Fortunately, learning how to fix a running toilet is among the easiest home plumbing fixes there is, and I have done it twice myself. The vast majority of the time, a running toilet is caused by an issue in the cistern. You don't need a plumbing licence to fix it, which is the other good thing. You should keep a towel nearby though because you might need it while fixing it.

Why Your Toilet Won't Stop Running

The running toilet problem is when the toilet keeps running water from the cistern into the toilet bowl. This, or a worse situation, can occur if the water runs past the flushing cistern and goes down the drain. This will not only waste water, but also cost you money. A running toilet can actually waste over 25,000L a year. I was quite surprised by this figure when I first heard about it. So, when it comes to learning how to fix a running toilet, there are three things you need to check in the cistern. They are the flapper valve, the fill valve, and the overflow tube. Often, one or a combination of the above are the issue. I remember the first time this occurred in my house; it was a warped flapper, nothing more. A quick trip to Bunnings, ten minutes and $15 later and the problem was solved. The best part about finding out what needs fixing when it comes to learning how to fix a running toilet is that it's easy to tell which part has gone bad.

How to Identify the Culprit

Before you go out and buy new parts to fix the issue, you should check it. You will need to remove the lid. Take care, ceramic ones slip when wet, and these are heavier than you think they should be. Next, flush the toilet. When the toilet flushes, does the water flow freely past the flapper valve or does it continue to run? In this scenario, the flapper needs to be replaced; often it is warped and the rubber is cracked or discoloured, but not always. Does the water run into the overflow tube after the flush? This means that the fill valve is not shutting the water properly (the float could be adjusted higher). Do you still hear a running toilet, even after the cistern is full? Most likely it is the fill valve. You can also drop a few drops of food colouring into the cistern water, wait fifteen minutes without flushing, and check the bowl. If the colour has seeped through, your flapper isn't sealing properly.

Fixing or Replacing the Flapper Valve

This is the biggest cause of a running toilet and the easiest way to fix it. You will need to cut off the water to your toilet; the tap is usually behind or to the side on the wall. Flush to drain the water out of the cistern. Unhook the old one from the overflow pipe. You can bring the old one into Bunnings or Reece Bathrooms to ensure the right replacement. They vary. Do not trust what the packages say; most of them do not say they fit all flappers. A flapper costs about $10 to $25. Simply fit the new flapper, make sure the chain is fitted and you are done. Make sure you have fitted it correctly. If you have too much slack, it will not allow it to lift when you flush; too much tension and it won't be closed properly. When it's in place the chain should be loose; it will open and close but the 10mm slack.

Adjusting or Replacing the Fill Valve

If your flapper valve is working properly but the toilet continues running, it's time to inspect the fill valve. This tall vertical valve located on the left side of your cistern controls the inflow of water following each flush. If it malfunctions, it may either refuse to shut off the water, resulting in constant running, or fail to fill the cistern effectively. The easiest step is to adjust the fill valve. Most newer valves have an adjustment mechanism on the body of the valve; usually, this is a screw or plastic clip. Rotate the adjustment clockwise to decrease the water level until the water is roughly 25mm below the rim of the overflow tube. If this adjustment doesn't resolve the issue, a new inlet valve may be the necessary solution. A new inlet valve for toilet cistern usually costs between $20 and $60, with popular brands like Fluidmaster and Geberit available at Bunnings Warehouse or Reece. To replace it, you'll need to turn off the main water supply, then detach the water supply from the underside of the valve, remove the old one, and install the new unit. The entire replacement process should take no more than 20 minutes if you work carefully. How to stop toilet running issues for good? Replace both parts at the same time! Since the flapper and fill valve are both relatively cheap, why wait to find out which part failed next?

When It's Time to Call a Plumber

The majority of toilet running problems can be handled by a handy home DIY enthusiast. However, there are instances where calling on a licensed plumber may be the wiser decision. If you've replaced both the toilet flapper valve and the fill valve but the toilet constantly running problem persists, then your cistern could be cracked, or a problem may lie with the cistern's flush valve seat that needs to be attended to by a professional. Some older properties might have a cistern toilet system with non-standard fittings that are not readily available to purchase. If your home is older than the 1990s, the insides of your toilet cistern or bath cisterns might be an uncommon design that won't fit current cistern replacements. A local plumber will know where to find compatible cistern parts or advise on the viability of replacing the whole cistern toilet at the current market price. A plumber should be able to diagnose and fix a running toilet for anywhere between $150 and $300 depending on where you're located in Australia. However, it's generally better to get at least two quotes when you suspect you'll need more extensive repair. And if your lavatory cisterns are more than 15 years old, replacing the entire suite might actually save money in the long run compared to repeated repairs.