Toilet Tank Not Refilling (Plus Backing Up)

House Repair Talk

Help Support House Repair Talk:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Dec 17, 2021
Reaction score
Montreal Quebec
I am writing on behalf of a friend whose toilet I do not have access to today - will check it tomorrow.

The tank will not refill when the flush lever is activated. In addition, the toilet was blocked with you-know-what, but I suspect this is not the primary issue as my friend was able to plunge the stuff more or less out down the drain. This blockage problem appears to be a one time event, whereas the failure of the tank to refill completely has been there for awhile.

Based on a little Internet research, it appears the problem is either the flapper or the toilet fill valve. I am guessing that replacing the flapper is easier to do, although I am aware one must match the type of flapper. With respect to the fill valve, one YouTube tells me that you can get a “universal” fill valve to replace the one that might be defective - can anyone confirm this?. You should know that this is an extremely old toilet, and I suspect this increases the risk that it would be difficult to find the correct replacement parts.

My strategy is to 1st try to determine if there's a problem with the flapper. Can anyone tell me how to determine if the flapper is not sealing well? Assuming that the flapper is not problem, I guess by process of elimination I would conclude that the fill valve is defective and needs to be replaced. In other words, I would be inclined to not even try to check if there's a problem with the fill valve (if that is even possible). Assuming that I could either use one of these universal fill valves, or otherwise find an appropriate fill valve, I would then proceed to try to replace the fill valve myself. Based on the youtube, it does not seem exceedingly difficult. I am aware that you have to shut off the water first.

Does all this make sense? Any recommendations and suggestions eagerly solicited. I am concerned about the possibility that by tinkering this by myself, I could conceivably make the situation worse. But I would guess the worst case scenario would be one where there is some sort of water leak, but I assume that this could be dealt with by turning off the water supplied to the toilet.
These repairs are fairly rudimentary.

Remove the tank lid and post a photo of the internal parts.

Manually add a gallon or so of water and look to see if it dissipates, which would indicate a leak or lack of seal at the flapper, and the flapper may no be the culprit.

Here are a a couple of flush valves, both of which are repairable, in place;

Identifying all the parts in a toilet tank
The 2nd is an older type which your photo may depict.
I attached 2 photos. First, I am concerned that there does not appear to be a mechanism to turn off the water to the toilet. There is no obvious lever or control mechanism at the base of the braided tube. I assume that unless I can turn off the water, there is nothing I can do to repair the toilet. Please confirm.

The second photo shows the inside of the tank. I am no expert, but it appears to me that this is a very old fill valve. Here is some additional information that may be relevant. When I fill the tank manually with buckets of water, the toilet indeed flushes. But it does not refill. And it doesn't even make a noise of any sort. However, and this is the strange part, when I first arrived in the apartment, there was a faint hissing noise coming from the tank, as if water was very slowly entering the tank. That is when I added additional water and tested to see if the toilet would flush and, as above, it did.
Any recommendations welcomed.


  • PXL_20240203_181349508.jpg
    2.3 MB · Views: 0
  • PXL_20240203_181332762.jpg
    2.3 MB · Views: 0
I will tell you what I know on your setup.

First you do need to shut off the water to do any repairs. You don’t have a shutoff behind the toilet where the pipe comes thru the wall. That is not that uncommon and you have to trace that line back to find out where the valve is. Many times people had put a large shutoff in the basement below the first floor toilet. Many times when you do find one where it is supposed to be it is stuck from never being used and you still have to find another valve. The worst case would be you would have to shut off the main water supply valve to the house. When you get the water shut off you may want to add the proper valve behind the toilet. The ones I like best are the quarter turn ball type valve.

The fill valve with float on arm made from brass tells me yours looks to be pretty old. The new one that would be a replacement that I like best is the Fluidmaster brand.

They work well and have a ring around the base tube that lets you adjust the overall height. That ring also allows you to pull the whole assembly off leaving the base tube. This is nice in the future as you can buy a new one for 9 bucks shut off the water flush the toilet and yank the unit out leaving the old base and pop the new one on in less than a minute. For that price and ease you just change them and don’t even try and figure out what the problem is. I have all mine set up with Fluidmaster filler valves and I keep 1-2 hanging on a nail in the workshop.

The flapper is likely still working. The way to test it is fill the tank and add some food coloring and wait a couple hours and see if the water in the bowl is tinted. If it is then replace the flapper unless your water is free.

There is a video on the ACE hardware page I linked showing how it attaches and how you adjust it.

There are all kinds of flappers you will need to maybe pop the old one off and take it with you to make sure the new one is the same size etc.
Aha, your fill valve is even older, but, should you chose, still repairable. With the water off, loosen the 2 screws and remove the cap and float arm from the fill valve, and inside you'll find a plunger and a couple of washers, which are likely available at ACE IS THE PLACE.

Also after you've shut the water off and disconnected the WC supply hose, use some CLR to clean the fitting and add the valve to the existing fitting.

If you find the flapper leaks, lift it and feel the tank gasket for rough surface, because that can also be the cause of apparent leaking in the flapper.