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Toilet Constantly Running? What’s wrong and how to fix it.

Published October 27, 2024
Written by Eric Smith

Why Is Your Toilet Constantly Running? 

Our master tradesman lays out the most common causes of one of the most common plumbing repairs and how to fix the most common issues quickly in this guide. 

A toilet constantly running isn’t just an annoyance—it can waste thousands of gallons of water each year and drive up your utility bill. Understanding how to fix a toilet that keeps running can save you time, money, and frustration. Here are five common causes of a running toilet and how to resolve them, with expert tips straight from the field.

1. Broken or Stuck Toilet Handle

If your toilet handle feels loose or sticks in place, it may not allow the internal flush mechanism to fully reset, causing continuous running. A simple handle replacement can solve this, but let’s get specific.

Master Tradesman Suggestion:
Look for corrosion or mineral buildup around the handle linkage. If the handle feels stiff or squeaks, apply a bit of plumber’s grease to the moving parts after installing a new handle. Pro Tip: When replacing, don’t overtighten the new handle—this can actually damage the tank or handle, leading to leaks and further issues.

2. Faulty Flapper Seal

The flapper seal is a rubber part at the bottom of the tank that holds water until the flush is activated. Over time, this seal can warp or wear out, leading to a slow leak of water from the tank to the bowl.

Master Tradesman Suggestion:
When inspecting the flapper, feel for brittleness or any rough spots. A worn flapper won’t make a complete seal, causing water to leak. Replacing it is a straightforward fix, but be sure to check the chain length. A chain that’s too short can pull on the flapper, preventing a proper seal, while one that’s too long can get tangled. Pro Tip: Once you’ve replaced the flapper, flush a few times and watch for any tiny bubbles in the water—these can indicate an incomplete seal.

3. Leaky Fill Valve

A fill valve manages the water flow into the toilet tank. If it’s leaking, you’ll often notice water trickling from the tank into the bowl, even when the toilet isn’t in use.

Master Tradesman Suggestion:
To diagnose a leaky fill valve, listen for a faint hissing or water trickling sound when the toilet hasn’t been flushed. Open the tank and observe if water is flowing into the overflow tube. Tightening the valve’s fittings can sometimes solve the issue, but if the valve itself is cracked or worn, replace it. Pro Tip: When replacing the fill valve, flush the water line for a few seconds before installing the new valve. This will prevent sediment from building up, which can extend the life of the new part.

4. Misadjusted Float Height

The float height controls how much water fills the tank after a flush. If the float is set too high, the water will overflow into the tank’s overflow tube, creating constant running.

Master Tradesman Suggestion:
With the tank lid off, watch how the float responds to water flow. The float should rise with the water level and stop when the water reaches about an inch below the overflow tube. If it’s too high, gently bend the arm downward (for older ballcock floats) or adjust the screw on the float cup. Pro Tip: Mark the water level before and after adjusting the float height to ensure it’s within the correct range. If the float doesn’t move smoothly, check for sediment or mineral buildup around the float arm.

5. Long or Misaligned Refill Tube

The refill tube is a small, flexible tube that refills the bowl after each flush. If it’s too long or incorrectly positioned, it can lead to a continuous flow of water into the overflow tube, creating an endless cycle of refilling.

Master Tradesman Suggestion:
The refill tube should be trimmed so that it sits just above the overflow tube and doesn’t extend down into it. Pro Tip: Use a clip to secure the tube just above the overflow opening—this simple trick prevents it from sliding down over time. After trimming, flush a few times to confirm the water level in the bowl is stable.

How Much Does It Cost to Fix a Constantly Running Toilet?

Wondering what it might cost to fix a toilet that’s constantly running? The good news is that most basic repairs are straightforward and relatively affordable. Depending on the exact cause, a professional plumber can often resolve running toilet issues for a cost between $200 and $500.

This investment not only ensures the problem is fixed correctly the first time but can also save you from higher water bills and prevent more significant water damage down the road. Our team at Austin Plumbing, Heating, Air & Electric is equipped to quickly diagnose and fix running toilets, providing you with lasting peace of mind and the assurance that your plumbing system is in expert hands.

Considering a DIY approach? While it might be tempting, remember that DIY fixes often miss underlying issues that a trained eye can spot. We recommend consulting a professional if you’re unsure—especially for peace of mind and a job done right!

If you’ve tried these steps and still can’t pinpoint the issue, don’t hesitate to call Austin Plumbing, Heating, Air & Electric. With decades of expertise, we’ll handle your toilet constantly running issue efficiently and ensure it’s done right. Contact us today to get help from trusted plumbing experts who serve Southeastern Wisconsin!

About The Author: Eric Smith
Eric Smith is a 3rd generation State of Wisconsin Master Plumber, Water Well Pump Installer, Plumbing Contractor, Water Well Contractor, HVAC Contractor and Water Treatment Expert and the owner of Austin Plumbing, Heating & Air.