I have completely turned off the water valve to the toilet but water is still flowing through. How do I fix it?

You can repair it, replace it, or leave it alone. It's your call. In all cases you will have to shut off the house main water valve. Inspect the valve, how it's made, and how it attaches to the stub-out pipe. OR you can just keep the house main shut until you complete repairs to the toilet, and just turn it back on, leave the toilet stop in open position.

You can also install an "add-a-valve" inline stop valve with swivel compression fitting on the bottom, in line with the toilet supply.

In almost any scenario, you would be ahead to get assistance from someone that knows what they are doing however. If a stop is threaded, use a backup wrench on the pipe to keep it from turning while you remove the stop to replace it. In the case of a compression stop, you should use a wrench on the nut and the stop to get the force you need; I usually tell anyone that asks to tighten it until it starts to scream (metal on metal squeal). If the old stop is sweated onto copper pipe, then I would call in a pro.
I personally don't recommend attempting to repair a non-functional stop, or leaving a non-functional stop in place; I know too many people that clog a stool from too much toilet paper. A new quarter turn stop is inexpensive, and will work flawlessly for many years.

if you can identify the valve (brass craft has their name on the handle) you can buy the exact same valve, remove the handle and stem and swap the new for the old.

quote; I usually tell anyone that asks to tighten it until it starts to scream (metal on metal squeal).

And, I usually tell workers that if it "squeaks it leaks".

I have never had one leak yet. I guess until someone starts using a torque wrench and gets an exact measurement we can just disagree.

Quote: I personally don't recommend attempting to repair a non-functional stop, or leaving a non-functional stop in place; I know too many people that clog a stool from too much toilet paper.

What does a non-functional stop have to do with a paper-clogged stool? If the fill valve and flapper are doing their job, the supply water will shut off. Any overflowing from a clogged stool will come from back-up or other causes downstream, which is entirely a separate issue.

It has been my experience that in certain situations, where the piping, shut-offs, etc. appear to be old, and might cause other problems, it is easier to just shut off the house main and replace the faucet or rebuild the toilet, etc. I understand BEST PRACTICE service, but some clients are old, on fixed incomes, single moms, etc. and just want the drippy faucet or running toilet fixed, and don't have the money to pay for turning a simple job into an all-afternoon affair replacing stop valves that they either didn't know existed, what they are for, or how they work, and might not possibly ever use as long as they live there. I do show them where the main shut off is.

"What does a non-functional stop have to do with a paper-clogged stool? If the fill valve and flapper are doing their job, the supply water will shut off. Any overflowing from a clogged stool will come from back-up or other causes downstream, which is entirely a separate issue."

WHen you have a blockage in the trapway, the water in the tank empties into the bowl. On some toilets, that means the bowl fills to the rim but doesn't overflow. The water entering the stool from the refill tube on the fill valve designed to add water to the bowl to bring it to the correct level will cause an overflow. Unless you shut the water off at the angle stop, it will continue to overflow; not everyone can sprint across the house and down the stairs and across the basement to get the water shut off at the main before disaster occurs.

The original post asked how to fix the stop, not whether it should be done; the obviously want the problem fixed, not bypassed.

quote.. "I understand BEST PRACTICE service"

i'm glad you do because i don't ????

to some people the more money they spend relates to a better job.
to some of us saving a struggling senion citizen or a single parent a few bucks as they live from crisis to crisis means sleeping well at night.
just to be clear, there are jobs that require a cadillac type repair and there are those who just need a band-aid until next time.
BTW, when i am leaving these band-aid jobs an the poor senior citizen is sitting there with their checkbook in hand. i tell them i will send my bill in a couple of days. (sometimes i forget to send the bill) i do sleep very well at night..

Quote

BTW, when i am leaving these band-aid jobs an the poor senior citizen is sitting there with their checkbook in hand. i tell them i will send my bill in a couple of days. (sometimes i forget to send the bill) i do sleep very well at night..

Our Creator will bless you and keep you safe.



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638