

A running toilet is more than just an annoying inconvenience—it’s also a major waste of water that can significantly increase your utility bills. In fact, a constantly running toilet can waste up to 200 gallons of water per day if left unchecked. While jiggling the handle might provide a temporary fix, it’s important to address the root cause to prevent long-term damage. If your toilet keeps running, don’t worry—this guide will walk you through the common causes, step-by-step troubleshooting, and how to fix the issue yourself before calling a plumber.
Why Does My Toilet Keep Running?
A toilet works by using a fill valve, flapper, and float system to regulate water flow. When you flush, the flapper lifts, allowing water to rush into the bowl. Once the tank empties, the flapper reseals, and the fill valve refills the tank until the float rises to the correct water level and shuts off the water supply.
When a toilet keeps running, one of these components isn’t working correctly. Here are the most common culprits:
- Worn or Damaged Flapper – The flapper is the rubber seal that controls water flow between the tank and bowl. If it’s old or damaged, water can continuously leak into the bowl.
- Faulty Fill Valve – The fill valve controls water entering the tank. If it’s malfunctioning, the toilet won’t stop refilling.
- Flapper Chain Issues – If the chain is too short or tangled, it can keep the flapper open, causing constant water flow. If it’s too long, it might not lift the flapper properly for a full flush.
- Improper Float Adjustment – If the float is set too high, excess water spills into the overflow tube, keeping the toilet running.
- Overflow Tube Problems – If the overflow tube is too high, water may continuously leak, preventing the tank from properly refilling.
Now that you know the possible causes, let’s dive into the step-by-step solutions to stop your toilet from running.
Step 1: Check the Flapper
Since a worn or damaged flapper is the most common cause of a toilet that keeps running, this should be the first thing you inspect.
How to Inspect and Replace the Flapper
- Turn off the water supply valve, usually located beneath the toilet.
- Remove the toilet tank lid and flush the toilet to drain most of the water.
- Reach inside and inspect the flapper. It should be soft and flexible, not stiff or cracked.
- If it’s damaged, disconnect the old flapper from the flush valve and attach a new one.
- Reconnect the chain, ensuring there is just a slight bit of slack.
- Turn the water back on and test flush the toilet.
Pro Tip: If you’re unsure which flapper to buy, take the old one to a hardware store and find an identical match.
Step 2: Adjust or Replace the Fill Valve
The fill valve is responsible for refilling the tank after every flush. If it’s faulty, your toilet keeps running because it won’t shut off the water flow properly.
How to Test and Replace the Fill Valve
- Lift the float arm (if your toilet has one) while the toilet is running. If the running stops, the float needs adjustment.
- Adjust the float height by turning the adjustment screw (newer toilets) or bending the float arm slightly downward (older toilets).
- If adjusting doesn’t work, the fill valve may need replacement:
- Turn off the water supply and flush to empty the tank.
- Disconnect the water supply line and unscrew the locknut holding the fill valve in place.
- Insert a new fill valve, tighten the locknut, and reconnect the water supply line.
- Turn the water back on and test for leaks.
Pro Tip: If your toilet has a ball float, consider upgrading to a modern fill valve with a vertical float for better efficiency.
Step 3: Inspect and Adjust the Flapper Chain
A flapper chain that’s too short or too long can prevent the flapper from sealing properly, causing a constant water leak.
How to Adjust the Flapper Chain
- Check if the chain is tangled or too tight, preventing the flapper from closing fully.
- If the chain is too long, it may get caught under the flapper. Shorten it by adjusting the hook position.
- If the chain is too short, it may prevent the flapper from fully sealing. Extend it slightly.
- Test the flush to ensure the chain allows the flapper to open and close freely.
Pro Tip: Leave about 1/2 inch of slack in the chain to allow smooth operation.
Step 4: Check the Overflow Tube
If your toilet keeps running even after adjusting the flapper and fill valve, the overflow tube may be the issue. If the water level is too high, water continuously drains into this tube, keeping the fill valve open.
How to Fix an Overflow Tube Issue
- Look inside the tank to see if water is spilling into the overflow tube.
- If the water level is too high, adjust the float height to lower it (refer to Step 2).
- If the overflow tube itself is too high, it may need to be shortened. Use a hacksaw to trim it down so that it sits at least 1 inch below the fill valve’s critical level mark.
When to Call a Plumber
If you’ve gone through these steps and your toilet keeps running, it may indicate a more serious plumbing issue. Consider calling a professional plumber if:
- Your toilet continues running despite replacing the flapper and fill valve.
- You suspect high water pressure is causing the issue.
- There are cracks or damage in the toilet tank.
- The overflow tube is improperly sized and requires more extensive repairs.
At Emergency Master Plumbing & Air, our experienced plumbers can diagnose and repair any toilet issue efficiently. We offer same-day service to stop your toilet from running and save you from high water bills.
Final Thoughts: Stop Your Running Toilet Today
A toilet that keeps running is not only frustrating but also costly in wasted water. Thankfully, most cause like a worn-out flapper, faulty fill valve, or improperly adjusted float—are easy to fix with basic tools and minimal effort. By following the steps outlined in this guide, you can stop your toilet from running and avoid unnecessary plumbing expenses.
However, if the issue persists, don’t hesitate to call the experts at Emergency Master Plumbing & Air for fast, reliable repairs. Contact us today and let us help you get your toilet back to working efficiently!