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How to Fix a Running Toilet

a white toilet with a hand ready to flush it.

A white toilet with a hand ready to flush it.

A couple of months ago I received the common call: "MOM... The toilet is running...and it doesn't stop!" After removing the tank lid, I could see the exact cause of the problem: 

The float arm was broken.  
the inside view of a toilet tank showing the name of its parts

I tried to fix it by only replacing the float arm (cheap, I know), but it was impossible to get rid of the small rusted pieces where the float arm connects to the ballcock. So, instead of only replacing the float arm I went ahead and replaced the whole ballcock with a fill valve, in the end it's going to save us water and troubles later on.

A month later, the same problem popped in my bathroom, the lift trap kept on getting tangled with the rusted pieces on the float arm, preventing the flush valve to close, another running toilet!  Look how bad it was:

Once again, it was time to get a fill valve,  I used the Fluidmaster Universal Toilet Fill Valve, no metal components :)
parts of a Universal toilet fill valve

  • Other materials, tools you'll need:
  • Bucket
  • Scissors
  • Wrench or pliers
  • x-Acto knife
  • Thread seal tape

thread seal tape, wrench and an X-acto knife

First, turn off the water supply and flush the tank.
how to get the water off the toilet water tank

In order to get an easier work area, the metal flanged tubing was completely disconnected.  The lock nut or flapper was then removed using a wrench.

Go ahead and remove the old ballcock and float ball.  Keep a bucket underneath if you still have water in the tank.

It's now a good opportunity to clean that tank.

Using a x-acto knife score the cone out of the shank washer.  Place the shank washer on threaded shank of the new valve.  The flat surface sits against the valve.

Install the new fill valve making sure the critical level mark on the valve is at least 1" above the top of the overflow pipe (it can be adjusted, even though I didn't have to do that).
Position the valve where the fill valve nipple is in direct position to the overflow pipe.  Push down on the valve shank...

While hand tightening the lock nut underneath the tank.  Do not over-tighten or the tank may crack.

I decided to change the metal flanged tubing for a vinyl/braided connector.

Using the coupling nut, the connector was then installed, using thread seal tape as an extra precaution to prevent leaks.

Finally, the refill tube needs to be inserted down into the overflow pipe, making sure it sits above water level, cut it with the scissors if necessary.  The other end is then connected to the fill valve nipple.

You can now turn on the water supply.

Take a big breath without worrying about water running after you flush the toilet.
White toilet with hand ready to flush it

There are many kinds of toilets, all of them with different mechanisms, the fill valve I used comes with complete instructions for different situations you may encounter, there were some extra parts in the kit I didn't need.

It was an easy and still very economical way (around $15), to extend the life of the toilet.


  1. Not the most beautiful post but definitely very practical! You are not only creative Cristina but super handy as well, you are my "Ana White"! Have a great weekend dear!

  2. Vel took the words right out of my mouth. You are my Ana White too!

  3. My goodness, you are so handy! Is there anything you can't do?! How awesome that you were able to fix this yourself for only $15 instead of hiring a plumber which would have cost way more! Awesome job, Cristina :)

  4. Way to go girl! There truly is nothing you can't do!

  5. Such good info! I am impressed, as usual! You go girl!

  6. wow, you are really handy, I don't think I would ever be able to do this or to even figure out where the problem was coming from first! :-) good job Cristina! :-) & of course thanks for sharing this with us too!

  7. Great tutorial! We have upgraded to fill valves in all out toilets, but have found that the water pressure in the feed line is really important. We had to tweak ours since if we have our lines "full open" the toilets kept running even with the new valves. When we shut the supply valve 1/4 turn the shut off worked correctly. Bizarre but true! I think the high water pressure was keeping the flapper up. *shrugs*

    Anyhoo.. I love your step by step instructions. Way better than paying a plumber!

  8. Wow Cristina que gran tutoríal,,, tu eres más maestra que yo ,,y yo si que me atrevo con todo ,,pero de gaitería ,,, nada

  9. We have a lot of running toilets in my house. This is a great tutorial! I'm stopping by from Home Stories A to Z. Have a great week!

  10. It’s great when I hear homeowners taking some responsibility for learning how to do basic plumbing jobs around the house. As a plumber with more than 15 years of experience I can’t even imagine how many toilets I have been called out to fix, and they generally are something to do with the ballcock, fixing leaks, or cracked pipes. I’m thinking of starting a few classes to teach very basic plumbing to homeowners, what do you think?

  11. I've been having this same problem with my toilet running and I think I'm having the same problem with the ballcock. I just thought something wasn't aligned right in my toilet. I've been pushing down the flush valve whenever it runs but this only fixes the problem temporarily. Looks like I just need to replace the whole fill valve. Is it always necessary to replace the whole thing?

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