Novice here. The fill valve was leaking and causing the water to coming very very slow. Like 45 minutes to fill up tank. I bought a fill valve top and replaced it. Let me add that I did turn water off at the supply valve but water was still trickling up the fill valve. Like the water was not completely shutting off.

After replacement I turned the water back on and the water would not stop coming in the tank. Even when the float lifted on the fill valve. I flushed and same thing. Turned water off again and water would very slowly start filling the tank.

EDIT: From comments I will have to replace the Fill Valve. My concern is the supply valve not completely shutting the water off. This is a older house so it would have to be shut off at the main. I don't know how to do this.

If there is very little water coming out from the supply valve could I still install/hook up the Fill Valve?

Thank you.

  • "I bought a fill valve top and replaced it" ? You have fill valve that is serviceable, Curious. Fill valves are usually sealed and cheap to replace the whole unit. 15 dollars and 10 minutes and you are in the modern age. Even your dad could do it. Maybe. – Alaska Man Apr 8 '20 at 20:25
  • Well it is probably 10 years old if not older. I was trying to do it myself and thought replacing the cap would be the easiest. You think the entire fill valve is bad? – Sam29 Apr 8 '20 at 20:29
  • I suppose my concern is that the water is not completely shutting off at the supply valve. There is still some coming out. Fill Valve replacement probably not a big deal... messing with supply valve gets into a whole other thing. – Sam29 Apr 8 '20 at 20:32
  • Your question is about the fill valve, fill valves live inside the toilet tank. If you are talking about the supply valve then you need to edit your question accordingly. – Alaska Man Apr 8 '20 at 20:49
  • 1
    Ack, I apologize for any confusion my edit of the original post may have caused. AlaskaMan was correct in his response that my question was really not on point. I originally posted about my father wanting to do the job but was hesitant to let him. When I did the edit I took this out. Thank you all for the help. – Sam29 Apr 9 '20 at 2:00

The proper way to address this is to turn off the water and replace both valves.

EVERY HOME OWNER should know where the main water supply enters the house and where the valve is located in their home. It may be coming out of the ground in a crawl space, in a wall behind an access panel, in the utility room where the water heater is or elsewhere.

If there is very little water coming out from the supply valve could I still install/hook up the Fill Valve?

Yes IF the flow is slow enough that you can capture it in container before the container overflows.

If the flow is significant then it is not practical.

I have done this more than once. Leave the supply hose attached to the supply valve and put the end that connects to the fill valve in a bowl or bucket. This may be difficult in the small space between the toilet and the wall. You may need a small bowl and that could result in having to empty it frequently while you are changing the fill valve. Fortunately you have a many places to empty it in a bathroom.

Doable but not exactly fun, two containers so you can have one catching the flow while you empty the other.

Install a new 1/4 turn supply valve and a new braided supply line if it is as old as the valve.

Edit: Jack makes a good point about the age of the valve. If your main valve is a gate valve it is probable that it may have issues shutting off completely or getting it open again. The only way to change that valve is to call your water utility company and have them shut off the water supply at the curb main shut off. Then you can install a new 1/4 turn valve, much nicer. If you do get it back on make sure you open it all the way, counter clockwise until it stops. It can leak if you do not. I flooded a basement once because i did not open it completely and it leaked, opening it completely stopped the leak.

  • Thank you for your help. This is a older house built in the late 50s, my parent's home. My father always took care of problems like this but just really isn't able to any longer. He always cut off at the water main at the road. I just asked him and he said there was a cut off up under the house in a crawl space but hasn't been used for years. Given the information I will more than likely risk the supply valve leak. Don't want the problem like you described. Thanks so much! – Sam29 Apr 8 '20 at 21:41

I agree with everything said however I would say that you should replace that shutoff in the crawlspace. If you're a newbie, you can use a push to connect ball valve, as with that you would need to do no soldering. Some people dont trust those, however they are easy to install and many professional plumbers use them. If you go out to the hardware store, make sure you also get a small section of the size pipe you are using (3/4 or 1/2) and a coupler. When you cut the old valve out you will likely be a bit short if you dont get a coupler and a new piece of pipe. And of course, MAKE SURE you shut off the water at the street before you cut the pipe. As for the toilet shut off, go ahead and do it while its leaking. You're likely to get more water leaking from the tank as you remove the old fill valve than you are from the leaky supply itself. If you replace that supply valve, go with a 1/4 turn variety. They are a couple of bucks more but the peace of mind is worth it.


I would hesitate to turn off the water at the main valve. If it hasn't been operated in years, you might not be able to turn it back on because the shaft to the gate could be rusted in half. If just a very small amount of water is escaping from the supply valve, you can try to tighten it up just a bit with a wrench to see if the water stops but be careful not to over tighten. You can also get a lot of towels and a bucket, get everything ready and loosen the nut for the fill valve, then the connection between the fill valve and the supply line and swap out the fill valve, tighten it up and reconnect the the supply line. Then worry about the possibly bad valves.

  • Thank you for your help. Given the additional information I will try replacement of the fill valve with supply valve leak. – Sam29 Apr 8 '20 at 21:45

Alaska Man has it right, however the leaky shutoff valve isn't going to get any better. So if you decide to replace the valve this is how I would proceed. Take a look at your main shutoff valve. Hopefully, it'll be in good enough shape to turn off - most of them are. If it is, shut it down by turning slowly.
Once it's off open the faucet on your bathroom sink to release any residual pressure in the system. Then slowly turn on the shutoff valve at the toilet with a bowl under it to catch any water that might be in the line. The stub coming out of the wall should be standard 1/2" copper. If the valve is held on with a compression nut, loosen it with a wrench, while holding the valve steady. Once it's loose you should be able to remove the valve by turning it and pulling.
When it's off replace it with another compression type valve like this one:
enter image description here
If the valve is not compression but is sweated on and there is 3 or 4 inches of stub behind it you can cut it off with a hacksaw right behind the valve and relace it with a Sharkbite style fitting like the one below that will push on to the stub.

enter image description here
You'll want to make sure you use some emery cloth or low grit sandpaper to clean the copper before pushing the valve onto the stub. From there you just reverse the steps to get it up and working again.

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