Mysterious Toilet Drip

One of my tenants has been saying for some time that they have a drip in one of their toilets, and I dropped in yesterday and took a look. It’s a slow drip - about one every few seconds. But I can’t figure out where the water is coming from or going to. There is nothing going outside the toilet. And the surface water of both the tank and the bowl seem undisturbed. But you can clearly hear it.

The tenant is concerned about it because they think it might be running up their water bill, so I said I would look into it. Any thoughts?

Sorry, I’m not sure I follow. Can you see or only hear the drip? Is it inside or outside the toilet? Is the floor around wet and if so where?

You can only hear it. The area around the toilet is completely dry.

Could it be inside the wall from the valve pipe? Or does it sound like it’s in the toilet itself?

Did you take the top off? It could be the valve dripping water into the tank or the hose dripping water into the over flow. It could even be water from another unit (or another room if this isn’t an apartment) dripping in the drain somewhere.

Something you can do is get one of those blue dye packs and put it in the tank. In a few hours, if the water in the bowl is blue, you’ll know if water is leaking from the tank to the bowl.

Also, shut off the water to the toilet and see if that stops the dripping. If not, shut off the water to the unit/house and see what happens. Both of these things may take a while for anything to happen. You could also try, after shutting off the water, flushing the toilet to get some of the water out of the tank and bowl (and away from overflow lines), but then keep in mind you’ll have to wait a while as things sort of drip dry,

Finally, if she’s convinced it’s the toiled and convinced it’s driving up her water bill, ask her if her toilet runs on it’s own from time to time. Unless she can hear it refilling, there’s not likely water running.

If the flapper isn’t tightly closed, water may drip into the lower part of the toilet. Put some food dye in the tank and see if the water in the bowl changes color.

Does your tenant say that the toilet “fills” itself at random times, too? It may be a small consolation, but if the tank’s not refilling, then no water is being consumed.

There is a seal between the upper tank and the top of bowl that could be leaking. However, water would be seeping out of the tank, its level would drop, and the fill valve would activate to re-fill the tank to the usual level.

This would also happen with a bad flapper, btw.

Turn off the valve on the supply line to the tank.

Does the “drip” still happen?
Does the water level in the tank change over time?

We had a similar issue. One culprit may be this: Try gently tightening the two bolts inside the tank (on the tank bottom). Or, drain the tank and replace the bolts along with their rubber washers. Do not overtighten! In other words, do not “crank down” hard on these bolts, or you could crack the porcelain tank.

FYI: Whether this is the answer or not, if you are wondering where the water is going, check the room directly below. It may be collecting inside the cover of a ceiling light fixture. This happened in our apartment long ago. Specific to my case described above, it was slowly dripping into the unfinished basement below making the ceiling insulation damp.

Is the toilet adding a little bit of fresh water to the tank periodically to make up for the water that’s flowing out?

Sorry, but not true.
If you have a leaky fill valve, the water level will rise to the overflow tube, and drain into the bowl. A slow leak will never cause a “fill cycle."

My comment was in response to water leaving the tank, not a leaky fill valve. I assumed the fill valve was doing its job w/o protest.

However, now that you mention it, the fill valve may not be closing all the way and water is streaming down the inside of that overflow tube.

Could be condensation on the inside of the tank lid, dripping into the tank.

What causes a fill cycle?

Thanks for all the suggestions, guys. I’ve ordered a dye tablet pack and we’ll see how it goes.

We have two bathrooms back-to-back (master and kids). When someone sits on the kid’s toilet, there’s a slow drip sound that’s very audible. A little investigating led to the drip sound coming from the stand-up shower drain in the master bedroom. It’s like a p-trap line is being flexed when toilet weight is applied, and the drip works its way to the shower drain. I can’t see any leaks anywhere, it’s just a weird configuration.

Yep. First step. Turn off the supply line to the toilet and listen.

I have a similar issue in my house. It just sounds like something is dripping from within the pipes somewhere. I always figure (hopefully and lazily) that it’s just condensation moving around grimy pipes. JohnGalt’s explanation gives me more confidence in my guess.

I have a toilet that does that. The drip is into the overflow tube. There are two possibilities, either the seal that lets water into the tank is leaking slightly, if so just replace the whole mechanism-they are cheap, or as was the case at my house, the water level setting in the tank happened to be right at the level with the overflow valve. You couldn’t see the water going in, but you could hear it. Literally, the surface tension appeared to keep the water in the tank. A quick adjustment (twice :frowning: ) fixed the problem. Make sure the full water level in the tank is below the level of the overflow pipe. I stared at it for a while and was never able to see any water actually going into the overflow tube. It was a very small amount. But enough to make a noticeable sound.

using the toilet. :slight_smile: