Plumbing: Troubleshooting Your Toilet's Flushing Mechanism

jnatiuk/stock.xchngA toilet's flushing mechanism is one of the easiest house parts to love. It may look like a Rube Goldberg contraption, but it's really a simple system of reliable, inexpensive parts that anyone can adjust or easily replace. If you take a few minutes to understand the system and learn what each part does, you'll soon realize that what used to be considered a plumbing emergency is probably nothing more than your flushing mechanism crying out for attention. It just needs a little love to go right back to doing what it does best. In the meantime, if you need to clear the bowl before you start working, use the Bucket Flush technique described below. 

How a Flushing Mechanism Works

A toilet's flush action is powered by three things: 1) water pressure, 2) gravity, and 3) you, the Flush Master. The big tank at the back is full of water, and it's elevated above the bowl. When the Flush Master activates the handle, it pulls on a chain inside the tank, which in turn lifts a little rubber trap door (called a flapper). This lets the water in the tank rush down through a big hole and into the bowl, creating the familiar swirling action and, ultimately, the flush that empties the bowl. When the tank is empty, the flapper drops back down over the hole. Meanwhile, a float that's attached to the flush-and-fill valve (also called a "ballcock") has dropped with the exiting water, triggering the valve to open and refill the tank. The float rides atop the rising water and shuts off the valve at the preset level.

Troubleshooting Checklist

Here are the most common causes and solutions with toilet flushing mechanisms. Keep in mind that most flusher parts cost well under $10, so don't spend a lot of time trying to repair old devices. Simply replace them yourself, or call a plumber to do it for you.

  • Nothing happens when the handle is depressed: This usually is accompanied by a "loose" feeling in the handle. Most likely the flapper chain has broken or detached from the handle arm. Inside the tank, reattach the chain (leaving it a little slack). If it's broken, use a thin wire or twist-tie to reconnect the broken ends as a temporary fix, and replace the chain soon (or wait to see how long the twist-tie holds out).
  • Toilet refills by itself: If your toilet automatically refills for a few seconds periodically, it's probably because the flapper is not sealing properly, allowing water to trickle into the bowl. When the tank gets low enough, the fill valve opens and tops off the tank. Make sure the flapper is down all the way. If the problem continues, replace the flapper (doesn't require tools).
  • Toilet runs (refills) continuously: If the refill sound never stops, check inside the tank. If it's empty, chances are the flapper is hung up on its own chain and won't close. If it's full, lower the adjustment on the flush-and-fill float (or bend down the metal arm with ball-type floats). Still won't stop? Lift up on the float or float arm; if the valve doesn't close, you have a bad fill valve. Turn off the water supply at the fixture shutoff valve (on the wall behind the toilet and has a football-shaped handle), buy a new flush-and-fill valve, and install it as directed by the manufacturer (it's easy). 
  • Flush is weak or incomplete: Observe the inside of the tank during a flush. If the flapper closes before the tank is more or less empty, replace the flapper. If the flapper seems fine, try raising the water level by moving the float up on the flush-and-fill valve (you can't go higher than a bit below the top of the overflow pipe, the vertical, open-ended tube inside the tank). Unfortunately, a poor flush also can be caused by a partial clog in the toilet or drain line.

The Bucket Flush

Sometimes flushing mechanisms don't play nice, and they decide to go on the fritz right after you've used the toilet. Here's how to handle the situation: Fill a bucket with 2 to 2 1/2 gallons of water (you might need less for a water-saver model), and pour it all straight down into the bowl, aiming at the hole in the bottom. Do this with confidence; it's the rush of water that creates the flushing action. The bowl will empty like it normally does at the end of the flush, but it might not refill, depending on your mechanical problem. The bucket flush won't hurt your toilet or plumbing, and you can do it as many times as needed until all is right with your flushing mechanism.

Philip Schmidt writes for

Updated March 8, 2018.

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