Water Torture

November 11, 2007 12:28 PM

Any plumbing jedi masters out there? Our toilet cistern drips and it's DRIVING US CRAZY!!

It's a Laufen. You push down on a button on top to flush, and the flush valve thingie looks very much like this.

What I think is happening is that water is dribbling from the cistern into the bowl, causing the ballcock unit to continuously drip water into the cistern in order to replenish the leaking water.

The water is not draining into the bowl through the overflow pipe.

We've had a plumber friend look at it - he checked and cleaned the ballcock seals and action, and the flush seals and said they seemed OK.

Of course, parts are nigh-on unobtainable even if we knew which part to get.

Please help us get a good night's sleep without resorting to turning the tap off every evening.

posted by TiredStarling to home & garden (8 comments total)

Sounds like the rubber plastic seal that covers the drain is leaking. This is normal, they dry up and crack and need regular replacing. Any hardware store should have it, pretty standard size.
posted by stbalbach at 12:33 PM on November 11, 2007

99% chance that the flapper valve, or its seat, is the source of your leak. Replacements are generally readily available at most hardware or home improvement stores.
posted by paulsc at 1:44 PM on November 11, 2007

I agree that it's the flapper valve. I had the same issue when dear younger cousin put tiny rocks in the tank and they abraded the rubber on the flapper valve--a constant, irritating leak.

If it's between sleeping and turning the water off, turn the water off.
posted by sondrialiac at 2:54 PM on November 11, 2007

If the water is dribbling from the cistern into the bowl, there are only three ways it can be doing that. From most likely to least likely: the flush (flapper) valve is leaking, the cistern is overflowing due to a leaky ballcock, or (much less likely, and dependent on cistern construction) the overflow tube itself is leaking. Those are basically the options.

If you look in the top of the cistern and you see that the top of the overflow tube is comfortably above the waterline, that rules out the leaky ballcock. If the dribble into the pan is affected at all by gently jiggling the flush button, the flush valve is the problem.

Even though your plumber friend may have cleaned the flapper valve, you might still find that it's hardened over time to the point where it doesn't make a good seal any more, or that it has a tiny ridge worn into it that has to drop exactly right into the drain to make it seal 100%. Replacing the rubber will most likely be a cure.
posted by flabdablet at 3:38 PM on November 11, 2007

Thanks for all the quick replies. Flapper valve! Gee, y'learn a new word every day!

stbalbach, when you say the seal that covers the drain do you mean the seal between the drain pipe and the cistern, rather than the flapper valve? There is a black seal there and I have noticed it's kinda crumbly in places. It's called the "valve seat" in the diagram in paulsc's answer.

The flush mechanism is not the traditional floating ball with flapper valve on a chain. It's inside a cylindrical plastic unit but I guess the principle is the same.
posted by TiredStarling at 4:14 PM on November 11, 2007

Taking one of these thing apart is not rocket science, and you will learn a lot by doing so. Just have a bucket of clean water handy to wash the scummy brown gunge off the bits and pieces as you take them out.

That brown scum, by the way, is not poo. It's mostly just clay and silt that's settled out of the water, though there will be some bacteria growing in there. It won't make you any sicker than picking your nose would.
posted by flabdablet at 5:17 PM on November 11, 2007

Oh, and that valve seat you mention will most likely be part of the drain pipe, rather than part of the drain pipe seal. That seal exists to stop water escaping from your cistern to the outside of your toilet, and provided it's not doing that, the seal is still doing its job. If it looks crumbly, though, it may start leaking if you do violence to your cistern in the course of getting the other bits out to inspect.

Inside your cylindrical plastic unit, you will most likely find a piston near the bottom with a flat rubber ring that actually plugs the drain; above that will be a float.

The way it's all supposed to work is that when the cistern is empty, the plug drops into the drain and blocks it. As the water level rises, water pressure on the top of the plug keeps the plug seated in the drain. As the water rises further, it submerges the float; but the float and plug are sized such that the buoyancy of the float isn't enough to overcome the pressure on the top of the plug, so it stays seated.

When you push the button, you supply some extra force to tug the plug out of the drain. At that point, the float takes over and lifts the plug clear of the drain until the cistern empties again.

If the rubber ring is worn or hard or cracked, water will leak around its edges, just like an old bath plug would. You should find that if you take the whole thing apart, and take the rubber ring with you to a hardware store, you should easily find a new one to match.
posted by flabdablet at 5:29 PM on November 11, 2007

TiredStarling, I meant the flapper valve just didn't know what to call it.
posted by stbalbach at 9:20 PM on November 11, 2007