Here’s How to Fix a Running Toilet Without Calling a Plumber

Photo credit: Klaus Vedfelt

Photo credit: Klaus Vedfelt

A running toilet isn’t just annoying. It’s downright expensive. “It’s like leaving a faucet running,” says Jeff Mezzatesta, owner of Mr. Handyman of Franklin and Brentwood. “Most newer toilets use 1.2 gallons per flush, so if a toilet keeps refilling throughout the day, you could be wasting between 30 to 50 gallons of water.” That adds up fast, and who wants to waste water anyhow?

There are several reasons a toilet will run, but two problems are the most common. The first issue is when the tank is constantly filling, which means the valve is not shutting off when it should. “And with valves that go bad, there’s no warning,” says Mezzatesta. “That’s why I recommend you keep a couple of these things on hand because I guarantee it will quit at 7 p.m. on a Sunday night when the stores are closing.”

The second common problem is when the toilet fills, then ten minutes later it fills again— but no one was in the bathroom (sometimes called “ghost flushing”). That’s likely due to a leaky seal or gasket, also called a flapper. Chances are, you’ll need to replace these parts about every 6 months to a year, depending on usage and how hard your water is.

Here’s how to diagnose and fix these common reasons your toilet is running.

How to replace a faulty flapper

If the toilet keeps filling itself up, even when no one is in the room, it’s probably a leaky flapper. The flapper is a flat rubber gasket inside the toilet tank that lifts to release water to fill the bowl. Over time, the flapper degrades, allowing water to trickle past it. Mineral build up from hard water or age, which causes the rubber to become less pliable and misshapen, may be to blame, says Mezzatesta. Test your theory: Take the lid off the tank, and push down on the flapper when the toilet starts running. If it immediately stops, replace the flapper. There are several different kinds so make sure you buy the exact same type (snap a photo before you head to the hardware store).

Before you start tearing apart the guts of your toilet, gather a bucket and some old towels or rags. Take a few photos of the setup inside the tank, including how long the chain attaching the flapper to the flush arm (handle). Now, shut the water at the line feeding into the toilet near its base; turn the handle to the right. Next, drain the tank by flushing and holding down the flush arm to get as much water as possible out of the tank, says Mezzatesta. You’ll be left with about an inch of water in the tank, which you can sop up with rags. You don’t have to disconnect the supply line that feeds water into the tank.

Now remove the flapper and follow the instructions that come with the new flapper. Make sure the flapper is flat and seated snugly into the drain hole. Re-attach the flapper chain to the flush arm with the same number of links used previously. If it’s too long, it’s going to run and you have to jiggle it to stop. If it’s too short, it won’t pull up enough for full flushes. Turn the water back on; let the tank refill, then flush to check if the flapper does its job.

How to replace a bad fill valve

If the toilet runs and runs, it’s likely time to replace the fill valve, which resembles a tower with a float on it. Again, don’t forget to take a few photos so you’ll know what goes where, and make sure you get the exact same type of replacement valve kit, says Mezzatesta. Now, drain the water as explained above.

Next, remove the valve by unscrewing and disconnecting the water supply line and locknut on the outside bottom of the tank. Keep the bucket and towels underneath this area to catch any remaining water. You may be able to hand loosen the nut, then use a pair of channel lock pliers to give it a quarter turn to the left. Hold the valve with your right hand, and take the nut off completely. Lift out the valve.

Now put the new valve into the hole in the bottom of the tank. As the right hand holds it in place, snug up the nut on the bottom of the tank. Finger tighten, or give it a quarter-turn with the pliers. You don’t want to overtighten it or you can damage it, says Mezzatesta.

The valve can be adjusted for height, so pay attention to where it was originally. Most replacements are set for standard height tanks, but if yours is taller, adjust accordingly (read the instructions that came with the valve). There also will be a refill tube, which may have to be cut to the proper length, that goes from the fill valve into the overflow pipe (the tower attached to the flapper on the other side of the tank). Turn the water back on and let the tank fill partially to check for leaks. If the seal is good, let it fill completely. Flush to test.

Is it difficult to fix a running toilet?

Not really. But you do need to make sure you purchase the correct parts, so take a look inside the tank before you head to the store. “Don’t be afraid of this job. It’s simpler than you think,” says Mezzatesta. “Just give yourself plenty of time, take lots of photos, and make sure to shut the water off first!” You can repair this yourself for less than $50, while a plumber or other home repair professional will charge $150 or more per hour.

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