Repair Running Toilet

Having to repair a running toilet is one of the most mundane yet costly issues in home plumbing. It can be expensive if the problem goes undetected, even if you can fix a running toilet yourself.

If you're on metered water and have received a shockingly high water bill, you know what I mean by expensive! That's because the water is constantly running from the tank into the bowl and down the drain.

Your choices are to either get out your tools for a do it yourself plumbing repair session, or to call a plumber for help. (Shameless self promotion... if you're in Portland Oregon, you can reach me, Brian, at Brians Plumbing Works- @ 503-656-6192. I have 30 years on-the-job experience in repairing running toilets.)

Fix a running toilet

Okay, you do-it-yourself plumbers, are you still with me?.... good! When you repair a running toilet, you'll find that any one of the three main parts in the toilet tank can be at fault.

Flush valve

When you must repair a running toilet the flush valve flapper is the most common culprit that causes running toilet problems. Lift the flapper and examine it for obvious wear, rot, or warping. If it has any of these three conditions, just replace it. If your toilet is one that has a flapper-less flush valve look it over as best you can.

The telltale sign of a leaking flush valve is the sound of running water echoing up the overflow tube of the tank. If by shifting or pressing the flapper or flush valve seal you can make the flowing water sound stop the problem is the flush valve.

If the flow is too slow to hear- try this trick-

  • Get some liquid food coloring
  • Put just 5 or 6 drops into the tank
  • Wait about 10 minutes to see if the color shows up in the toilet bowl.

There are so many toilets now that require a factory-style flapper, I can’t describe them all. The new three inch flappers seem to be especially proprietary. So to replace those flappers or non-flapper style flush valve parts, you'll need to get the part from a plumbing specialty supply source. Find one that will sell you what you need to buy instead of what they need to sell.

Take along the manufacturers name, the model info, and the worn-out part (if you know it is correct. Some parts aren't the originals.)

One more thing, if your running toilet problem is due to a worn-out brass flush valve seat, see if a Fluidmaster Flusher Fixer will work for you.

Fluidmaster toilet parts

There's a common flapper problem that isn't a flapper problem at all. Some people don’t read the instructions when they install the Fluidmaster 400 fill valve, Instead of attaching the primer tube by its adapter, they throw the adapter away and run the primer tube way down into the overflow tube.

This seems to work fine as the primer tube is too long to jump out of the overflow tube with the pressure of full flow. The only thing wrong with this is that the adapter was not only meant to hold the primer tube, but to create an air gap.

When it's pushed down the overflow, it sets up a siphon that acts and sounds like a bad flapper. The flapper is really okay. Water constantly siphons from the tank into the overflow until the fill valve float drops, opening the valve to refill the tank, and so on. Next thing you know, you must repair a running toilet.

This problem is so common that I keep Fluidmaster adapters in stock in my plumbing truck to replace those that have been thrown out. I get calls to repair running toilets from people who seem to know what they are doing and have put several new flappers in to solve this problem. Their refusal to read the instructions will end up costing them a service call.

Fill valve

You'll know if the fill valve is the running toilet problem easily enough. If it is, the water will be constantly flowing into the overflow tube. That's because the fill valve will no longer completely stop the flow into the tank. To repair a running toilet in this case, replace or fix the fill valve.

In either case getting the proper proprietary parts makes a difference when you repair a running toilet. A Fluid Master 400 series valve is the best general after market unit, and can be an upgrade for some older toilets with non anti-siphon fill valves. After you are done with the fill valve, perform the dye test described above, to make sure that there really was only the one problem.

Trip lever

If the trip lever is the cause of your running toilet, it's probably because it's not staying within its intended range. That allows the flapper chain to slip between the flapper and the flush valve seat.

The trip lever may also hang up. That keeps the flapper suspended off the flush valve seat. Replacing the entire trip lever solves both of those problems.

The trip lever problem that doesn’t call for a new lever is a lift wire that hangs up. Older style toilets that still use flush balls can also still be using lift wires connected to the trip lever to lift the flush ball.

Trip lever problems tend to occur off-and-on. So the easiest way to repair a running toilet may be the hardest to diagnose. Lift wires may work right 19 out of 20 times, and then hang up.

Setting new lift wires is no cake walk, I make apprentices watch me so I can show them my top bend. I keep my top lift wire bent at about the curvature of a quarter so it won't climb into the trip lever hole when it moves.

The bottom wire travels through the eyelet of the top wire. This allows the bottom wire and its flush ball to float free of the top wire. And the top wire can drop freely without dragging the bottom wire with it.

See my photos on my page How does a toilet work

After you repair your running toilet...

If you received a high water bill, be sure to call your local water district after you've repaired the running toilet. I've seen some Portland area water districts give a rebate... maybe yours will too. It doesn't hurt to ask!

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