Put a few drops of food coloring in the toilet tank full of water and wait. If the water in the toilet bowl turns color then the flapper valve in the tank is leaking.

If it's the flapper valve make sure that the replacement you get is correct for your toilet. The red flappers last longer on chlorinated city water. Use the scrubbie side of a common sponge to clean the area where the flapper seats.

I secound what Lurker says and you can skip the food color because your vinigar test already proved it's the flapper. Although you don't need a plumber for this, I would suggest you shop around for a different plumber than the one who replaced the tub facuets becase of whistling.

I like the food coloring test to sustain what the OP suspected with the vinegar test. Visual confirmation is incontrovertible.

Thanks all for the replies.

In fact I tested again tonight. Water valve to toilet turned off. Water valve to sink and tub turned on. Ran water in the sink first for about 30 seconds, turned off the sink faucet and listened. No dripping sound. Ran water to sink and tub at the same time for 30 seconds to a minute. Turned off both faucets and listened. No dripping sound.

The only time I get a dripping sound is when the water valve is turned on to the toilet. But what I do not understand is if there is no or very little water in the tank (because I'm holding the arm that keeps the tank from filling), how could it be the flapper? And what am I hearing behind the wall given that the tank is not filling? Thanks.

Pull out the end of the skinny fill tubing that clips to the top of the overflow tube. Is it dripping?

Sorry jerry,we occasionaly overlook walking a person on through it once it's known where the problem lies.
Remove the tank lid as you did when holding the lever up.
Flush while looking into the tank. The rubber part that was pulled up by flush leaver is the "flapper". When the tank has water in it , water is leaking under the flapper as if the handle was pushed only enough to lift flapper 1/1000th of an inch. The drip you hear is that water falling about 8" into the rear of bowl. Given enough time the tank leaks enough water the the arm you have been holding falls 1/2" and refills the tank. Any questions?

Hey Lurker, your food color test is the best in the west and certainly wouldn't hurt any thing but I was only trying to save jerry any farthur looking considering all that had been done already. I assumed the vinigar was colored and another colorant would only be redundant. Actually the occasional refill noise sealed the deal on what was wrong.

Homebound,

I'll check that and get back to you. At the moment I'm at work.

@ klem1

You know that and I know that but the OP seemed intent on proving to himself that the problem wasn't elsewhere. Food coloring leaking from the tank to the bowl is hard to ignore unless you don't try it..

I've found that people are unwilling to accept a leaking flapper cause there's no catastrophic damage to see to sustain the failure of the flapper. Flapper looks OK so the problem must be somewhere else.

If the OP would listen to what we're telling him and either try the food coloring to prove or disprove the flapper leak or just replace the flapper it would either resolve the problem or he does have a leak inside the wall and then... $$$$$$

Klem1,

Thanks for the info. "The drip you hear is that water falling about 8" into the rear of bowl." - that is what I've been looking for, an explanation as to what the dripping noise could be, other than a pipe leak. So you are saying the dripping sound that I hear is actually an echo up the pipe from the water falling into the rear of the bowl?

The question of the source of the dripping sound behind the wall is very important question because if it is a pipe leak, at some point soon I need to open the wall and deal with any potential mold.

I like the flapper theory, although I admit that I still don't understand how with almost no water in the tank I could be hearing dripping sounds from due to a defective flapper.

Of course the next step is to actually replace the flapper and see what happens.

"Flapper theory." %$%$!!!!

Do....the....food....coloring...test.

jerry,

Stop thinking and do what we are telling you to do. The WHY will come when the HOW is executed. It is annoying to debate with people who ask for help and then ignore the unanimous recommendation made by people who are offering the help you asked for and who know what they are talking about. Makes me feel like I'm wasting my time.

If you do the food coloring test and it shows up in the bowl then the flapper is leaking... no ifs, ands, or buts. If the dripping sound stops when you replace the leaking flapper then you have your answer. It is as simple as that. If the dripping sound doesn't stop then you had a bad flapper and you have another problem to resolve and we can move on with the diagnostic process knowing we've solved one problem.

If no food coloring shows up in the bowl then the flapper is good. We have eliminated it as a possible problem and you've actually taken a diagnostic step towards a resolution rather than being fixated on pondering an aspect of a problem you haven't taken a step towards finding. Until you eliminate the flapper as a possibility you haven't begun to narrow down the problem.

This post was edited by justalurker on Sat, Sep 21, 13 at 13:43

justalurker,

Perhaps I should have mentioned that I haven't had time yet to get a flapper and replace because I work 50-55 hours in the space of four days. I've been making these posts in this forum from work.

I have three days off coming up so I'll definitely replace the flapper during that time. As far as the food coloring test, there's no doubt in my mind that the vinegar made its way to the bowl, but an additional food coloring test wouldn't hurt.

So we're all not where the problem is?

Rather than rely on the nose knowing, the food color test will prove that the flapper is bad and is also the way to know that the replacement flapper is working properly.

Just to elaborate for you... when the flapper leaks, the water level drops, and the float opens the fill valve which allows water to flow into both the tank and through the little pipe directed to the overflow tube till the float shuts off the flow. Water directed through the little tube can sound like dripping when it falls from the top of the overflow tube to the water level way down the bottom of the overflow tube.

As I already said, you may have a flapper problem and another problem so eliminating one problem for sure is the way to find the other problem. Looking for two problems at the same time is the sure way to premature baldness.

UPDATE:

Definitely a flapper problem. On turning on the water to the toilet the tank was filling slowly because water was leaking into the bowl. I put my finger on the front edge of the flapper and the tank was able to fill in a more normal fashion. The dripping sound started immediately on turning on the water to the toilet.

After the tank filled the water level in the tank almost immediately started to drop. As it was going down I flushed the toilet again. Again I held down the flapper as the tank started to fill. Oddly the overflow tube started to fill up as the tank was filling and at one point started to overflow.

After the tank was full the water level in the tank started to fall again. I flushed and this time as the water was filling the tank, with the water level still low, I put in several drops of red food coloring (special wal-mart trip just for that... I don't cook). The red food coloring showed up in the bowl right away. So clearly its leaking into the bowl.

So the dripping sound is probably the water dripping out of the bowl and into the drain pipe for the toilet. What I don't user stand is why does it do that? Why would water drip out of the bowl and into the drain pipe, even when there is little or no water in the tank?

Of course next step is to replace the flapper. I bought a fluid master universal #501 flapper. I should have time to replace it Tuesday and report back.

Flapper leaks are usually small and the food coloring takes a while to migrate to the bowl. Seems that you have a massive flapper failure so noises may be exaggerated.

Make sure the universal flapper is correct for your toilet. Some new era 1.6 gpf toilets take specific flappers.

update 09/25:

Replaced the flapper which fixed the water leak from tank to toilet problem. Confirmed this by applying the red food coloring test. Not one drop of food coloring from tank to bowl.

As for the "dripping" sound from behind wall, the behavior has changed. Now, after a flush I can hear a fast dripping sound (with and without my ear to the wall) for the first minute to two minutes, then it slows to about one drip per second up to about three or four minutes. After four to five minutes the dripping sound seems to have completely stopped (although sometimes I think I hear a drop afterwards but it could just be normal plumbing sounds). I actually timed the dripping sound with a stop watch over several flushes.

So this is different than before I replaced the flapper. Before the flapper was replaced the dripping sound was constant and would never stop as long as the water was turned on to the toilet.

Is it normal after a flush for water to drip from the bowl into the drain pipe for a few minutes afterwards?

One side note is that it is possible I am hearing something which most people don't notice because I have extraordinary hearing ability in my left ear (my right ear is deaf and the left ear has over compensated over time. Audiologists love me because hearing tests for my left ear are literally off the charts, especially in high frequencies.)

Having said that, I don't hear the "dripping" sound after a flush from the other two toilets in the house, one upstairs the other downstairs.

At the moment I have the water turned off to that bathroom out of an abundance of caution. One question that I have is will the fact that the water is shut off to the upstairs bathroom cause unbalanced water pressure in the plumbing which could cause a pipe to leak or break? Especially when doing something like washing clothes in the upstairs washer?

Not many toilets are perfect so it takes a few secounds or minutes for things to "drip dry" after each flush. Nothing unusuale with that. Atenitive diy home owners rebuild the tank every few years just to know it is at it's best. I will not attempt walking you through a rebuild,the flapper wore me out already.
Turning the toilet off has no potential bad effect on remainder of plumbing. A toilet that has been off for a long time drys rubber parts and is prone to leak when water is turned back on .

Got it. Thanks Klem1 and all others who replied.

If you bought a universal flapper, it may not fit that well. So some minor leakage as it seats is not unexpected.

The inflow pipe inside the wall may have a pin hole leak.