Toilet Tank Not Filling: Causes And Solutions

Last Updated On May 26, 2022
Toilet Tank Not Filling Causes And Solutions

Normally, your toilet tank refills with water whenever you flush the tank. If the tank suddenly stops filling with water or you have a slow filling toilet, it won’t work properly. If you only have one commode in the house, this can create an urgent situation that you need to resolve immediately. Let’s talk about how to do this.

In this PlumbingNav guide, we will cover:

  • Toilet tank not filling
  • Why is my toilet tank not filling up with water
  • Things to know about a toilet that keeps running after flush

What's In This Guide?

      Toilet Tank Not Filling? 

      Toilet Basics

      Before we get started, it’s a good idea to learn about the basics of your toilet and how it works

      Your toilet has water in the toilet tank and the toilet bowl before you use it. How does that water get there?

      After you use the flush lever, water enters your toilet bowl from the refill tube in your tank so it’s ready to force the toilet water and contents out through your sewer line. 

      In order to allow water to enter the bowl, the handle opens the flush valve (sometimes known as a flapper valve due to the toilet flapper that covers or opens the valve). When you open the flush valve, the fill valve (or refill valve) will also open, allowing water to enter the tank through the supply line and subsequent fill tube. 

      The fill valve closes when a floater connected to the flush valve by a chain reaches the appropriate water level. (Remember this point when we troubleshoot a running toilet that won’t fill.)

      Toilets also come with an overflow tube in the event the fill valve doesn’t close as expected. The overflow pipe transports excess water out instead of letting the tank overflow. 

      Finally, toilets come with an individual shutoff valve. 

      Here is an overview video of how toilets work:

      Toilet Tank Not Filling With Water; Water Not Running

      In some situations, your tank won’t fill with water, and you will notice that there’s no water entering from your supply line at all. The first step is to isolate the problem and rule out a wider problem in your home.

      Do this by verifying you are still getting water at the other toilets and fixtures in your home. 

      If you notice that other fixtures are indeed getting water, you’ll know the issue lies with this specific toilet tank. We’ll discuss the components you can check shortly. 

      By the way, since you won’t be able to flush this toilet, here’s a hack. You can pour a bucket of water down to induce a manual flush while you troubleshoot the problem. This also works if you need to flush the toilet when the power is out

      Toilet Tank Not Filling But Water Is Running

      Sometimes, the water keeps running, but your tank simply won’t fill up. 

      Not only is a running toilet an extreme waste of water, but it makes it impossible to use your toilet properly since the water keeps running and won’t accumulate volume in the tank. We’ll talk about how to fix this, too. 

      Ok, now that we’ve laid out the basics and the two types of toilet tank problems let’s get into solutions. Here are the possible causes your toilet tank may not be filling with water and what to do about it.

      did you know Toilet Tank Not Filling

      Toilet Tank Not Filling But Water Is Running

      Sometimes, the water keeps running, but your tank simply won’t fill up. 

      Not only is a running toilet an extreme waste of water, but it makes it impossible to use your toilet properly since the water keeps running and won’t accumulate volume in the tank. We’ll talk about how to fix this, too. 

      Ok, now that we’ve laid out the basics and the two types of toilet tank problems let’s get into solutions. Here are the possible causes your toilet tank may not be filling with water and what to do about it.

      Why is My Toilet Tank Not Filling Up With Water?

      Toilet Shut Off Valve Closed

      All toilets come with a shut-off valve. 

      The shut-off valve allows you to turn off the water to the toilet without affecting the water throughout the other locations in your home. 

      First, examine the shut-off valve to ensure it doesn’t look damaged. One way to do this is to turn in both positions. Are the handle and valve pin stuck? Does it just spin, indicating a broken or “stripped” component inside? If so, you may need to deep clean the valve or replace it. 

      If the valve appears intact during test operation, verify it’s actually open by opening and closing the valve to put it in the right position.

      Here is a simple video to help with a stuck toilet shut off valve:

      Faulty Fill Valve

      Generally speaking, the main reason your toilet tank isn’t filling with water is a malfunctioning toilet fill valve. This is the component inside your tank that water passes through after entering through the supply line.

      The fill valve can become faulty due to buildup or age. 

      If water is passing through your supply line and your shut off valve is open and functional, this is the next best place to examine. 

      If you suspect this is your problem, clean the fill valve to the best of your ability. (Turn off the water supply first.)

      You may also want to look for a screw in the top of the fill valve. Loosening the screw may allow more water to enter the tank. 

      Here is a great video showing you how to troubleshoot a toilet fill valve:

      Low Water Pressure

      Secondly, your toilet tank may not fill with water due to low water pressure levels. 

      Your toilet may not be set up for low water pressure levels and shut off before filling up completely. 

      Toilets on the second floor may struggle more than toilets on the first floor thanks to the increased pressure required to force the water upward. If this is the case, you would also notice low pressure in nearby sinks, showers, etc. 

      You can increase your water pressure by adjusting the main valve settings, or by installing a special device.

      Here is a video showing how to increase water pressure:

      Here is a link to a common reducing valve similar to the one in the video: See here.

      Things to Know About Toilet That Keeps Running After Flush

      If you flush your toilet and it keeps running, you should turn off the water to your toilet before you end up paying for it in your water bill. Running toilets can waste up to 200 gallons of water every day. 

      The main reason your toilet will keep running after you flush is too much water in the tank causing overflow water to leak from the tank into the bowl. 

      In this case, you may be able to adjust the height of the float. 

      Alternatively, the problem may be a result of a flapper that won’t close properly.

      In order to tell if your flapper isn’t working, follow these steps before you call for plumbing services:

      • Remove the toilet tank lid
      • Flush toilet and wait for tank to refill
      • Apply food coloring to the water
      • Wait 20 minutes
      • Flush

      Watch: Adjusting the toilet float is a pretty simple fix. 

      If the water is still running the problem is likely the flapper. If any of the dye you put into the tank gets into the toilet bowl, there’s a problem with the flapper or a leak. 

      If you need to replace the flapper, you can find flappers with the chain attached online and Home Depot (to name a few). See our reviews of the best toiler flapper should you need a replacement.

      A Note On Toilet Efficiency 

      Toilets use the largest amount of water in typical household water systems (up to 30%). Therefore, the efficiency of your toilets can have a real impact and save money on your water bill

      The federal government has determined that toilets must not use more than 1.6 gallons per flush (GPF)

      Today, technology advancements have allowed manufacturers to produce Water Sense toilets. In order to receive a Water Sense certification, the toilet must operate at 1.2 GPF or lower. For people who want to go above and beyond when it comes to reducing their water use, some models come with a MaP Premium efficiency toilets that won’t use more than 1.0 GPF. 

      Final Thoughts On The Why Toilet Tank Not Filling Back Up With Water

      If you have an older toilet, it might be worth your while to look into a new toilet altogether. New models offer higher efficiency and advanced features, such as dual-flush technology and sometimes even heated seats. 

      If you utilize your DIY knowledge and still couldn’t resolve the issue, talk to your plumber about whether you will benefit from repairs or a new toilet installation. 

      FAQs on Toilet Tank Not Filling

      Why is toilet tank not filling but water running?

      If the tank isn’t filling up but the water keeps running, one major cause is a leak from the toilet tank to the toilet bowl or a problem with the flapper in your toilet tank. 

      Why is there no water coming into my toilet tank?

      If no water appears to enter your toilet at all, it can be a problem with the shut off valve located behind your toilet.

      What do you do when your toilet tank won’t fill?

      If your toilet tank won’t fill and you don’t hear any running water, start by checking your other toilets and fixtures. 

      If none of your fixtures receive water, test if other fixtures in the home are receiving water. If the problem only appears to happen at one toilet, verify that shut-off valve to the toilet is open. If it is, then check the fill valve inside the toilet to confirm normal operation. 

      Did you know there is such a thing as a tankless option? See our review of the best tankless toilets, here.

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      About Plumbing Navigator

      We write about "all things plumbing," helping you navigate common questions, repairs, and the best plumbing products on the market.

      About Plumbing Navigator

      We write about “all things plumbing,” helping you navigate common questions, repairs, and the best plumbing products on the market.

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