This Is a Hammer: Rectify toilet’s defective flush-out system

Q: I happened to read about the guidance you offer in the matter of fixing problems related to plumbing. The flush-out system in my house is defective.

When the lever is operated, water from the tank keeps flowing into the toilet instead of stopping and letting water fill up the tank again. This does not happen every time the lever is operated, but it does happen frequently. Could you please let me know what should be done to rectify the defect? — Bashker A.K., via e-mail

A: The main culprit in this case is probably the flapper valve. This large rubber valve (which literally operates like a flap, or in some cases looks like a little plunger or cap) is located at the bottom center of the reservoir tank. Its job is to allow water to flow into the toilet bowl for flushing, and to stop the flow of water when the flush is complete.

Watching how this valve works is actually kind of neat. Remove the lid of the tank and flush the toilet a few times, observing the valve at the bottom of the tank. When operating properly, a chain or metal rod lifts the valve up when you depress the flush lever (which is hooked to a simple lever system).

The valve stays up while the tank empties — pushed up by a small vacuum created by the water flowing rapidly out of the tank. When enough water has flowed out of the tank, the vacuum is no longer sustained, and gravity takes over, allowing the valve to fall back down in place over the outlet. The water then refills the tank and stops thanks to another leverage process in the flush assembly.

When this fails to work, it’s almost always because the flapper valve is getting hung up somehow. Sometimes the pull chain is too long and gets twisted, making it too short to let the valve down properly. Adjust the length of the pull chain so that it is not too slack and test the flush again.