Cistern Not Filling? Here's What To Do

Toilets are wonderful contraptions with a surprising amount going on to make them work. If your toilet cistern is not filling, it can be distressing and frustrating. Luckily, we have your back and can help you troubleshoot in no time! Most of the issues that cause a cistern not to fill can be addressed by you in your home, cutting out repairmen.

The most common causes of a toilet cistern not filling are the float ball, fill valve, line blockages, and more.

Keep reading for a comprehensive list of all that could be preventing your cistern from filling. Now let's get to it, shall we?

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Cistern Not Filling: The Causes and Fixes

As I said above, most of these issues can be addressed in a rather quick fashion. We'll start with the easier fixes, and move on to the more time-consuming ones. Let's start with the float ball.

Float Ball

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The float ball is by far the most common cause for a cistern not filling. For the unaware, the float ball is the little ball (or another rubber piece) that, well, floats. It sits in the cistern and, when water levels are optimal, prevents the cistern from filling or draining further. If it's not given enough room (or too much), it can prevent your toilet from functioning properly.

For those who work visually, check out this video guide on how to adjust a toilet float. Otherwise, follow the below steps:

1. Grab a Phillip's head screwdriver.
2. Locate your float ball; it should have a screw on the side.
3. Turn it clockwise (tighten it) until water levels are where they should be, roughly 5-10 cm below the overflow pipe.
4. Profit.

This will not only save you money on the water bill but will likely get your toilet working perfectly again!

Fill Valve

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The next stop on your troubleshooting trip should be the fill valve (assuming the float didn't fix the issue). This is the small valve located near the base of your toilet. These are what control the flow of water from your water supply to the toilet. Now, you'll (again) need a Phillip's head screwdriver, and should follow these steps:

1. Once you’ve located the fill valve, it’s time to work.
   • These are usually on the left side of the toilet toilet if they use a float arm (which you’ll see right away once opening the cistern).
2. Locate the adjustment screw (it should be the only screw on the fill valve) and rotate it clockwise, tightening it. This will allow more water into the cistern. If you need to reverse this or have less water in the cistern, simply turn the screw the other direction.
3. Flush to ensure everything is working properly.
4. If your toilet uses adjustable cylinders, do the exact same thing, but pinch the clip closed and slide it up or down as needed.

Hopefully, this solved your problem; if not, move down the list.

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Purposeful Blockages

Sometimes, rather than just fixing the valve or float, people choose to weigh down their cistern to change water flow. If you've purposefully added some heavy item to block water flow - move it! That is likely the cause of the problem.

And in the future, maybe try to fix things properly, rather than choosing the easiest momentary solution. That's how this stuff happens in the first place.

Trip Assembly

This is the handle attached to the flushing lever (or button). Generally, the issue with trip assemblies is that they were installed poorly, or at a less-than-ideal angle. To fix this, simply pop open the cistern and examine it for damage. If it's damaged, you'll need to replace it after ordering a new one.

If you're not comfortable with this, call a professional. You don't want to further damage the toilet or accidentally purchase the wrong part.

Waste Line

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If your toilet cistern isn't filling, but none of the above problems is the cause, it's possible that the toilet is simply clogged. The solutions are one of the following:

1. Plunge the toilet using a flanged plunger. If this doesn’t work, move down to step 2.
   • You can also use an auger to do clear the blockage, but that’s assuming that you have one. Everyone’s got a plunger, not everyone has an auger.
2. Check that the central vent isn’t clogged. You can clear this by flushing the vents in your toilet with hot water, though this is likely a job for a professional plumber. Often the clog is too deep for hot water alone to do the trick.

Water Pressure

If your cistern still isn't filling, take a look at your water pressure. There's generally a water pressure gauge attached to your central water heater - you're looking for roughly 80 PSI. If it's below that, it's likely that you need to have a professional take a look. There aren't many DIY fixes for poor water pressure, and many times, the issues lie in the home's plumbing. Whether that means that there's rust, mineral buildup, or something else preventing your home's pressure from being where it's needed, it's likely not a job for the average Joe.

This is where it's time to weigh your options. You've tried the easy fixes - is it worth your time and money to keep trying fixes and potentially replacing parts? If so, please, do it! If not, or if you're not too well-versed in plumbing, it's time to call for help.

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Final Thoughts

If your toilet cistern is not filling, there are several things to look at yourself before calling in a professional. Begin by ensuring nothing is purposefully added to block water flow. After that, take a look at the float ball, fill valve, and trip assembly in that order . After that, it's likely time to call for help. Not only will a professional plumber solve the issue faster than you will, but they'll also do it better.

There are a lot of things that can go wrong with toilets, and some of them involve dealing with plumbing and your home's actual water setup. If nothing above solved your issue, it's time to sit back, make a drink, and let the pros do their jobs.