Few sounds are more irritating — or more wasteful — than a toilet that won’t stop running. Beyond the annoyance, a constantly running toilet can waste up to 200 gallons of water a day, driving up your utility bill fast. The good news? Fixing it usually takes just a few minutes and a simple adjustment or replacement of one inexpensive part. Here’s how to diagnose and fix the issue yourself — no plumber required.
Step 1: Remove the Tank Lid and Identify the Problem
Lift the lid off the toilet tank and set it aside carefully. Inside, you’ll see a few key components: the flapper, the float, and the fill valve. These are usually responsible when water keeps running.
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If water is spilling into the overflow tube, your float is set too high.
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If the water never fully stops filling, your flapper might be leaking.
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If water continues trickling after flushing, the fill valve may be worn out.
Take a moment to observe what’s happening — this will tell you exactly which part needs attention.
Step 2: Check and Adjust the Float
Most running toilets are caused by the water level being set too high. To fix this:
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Locate the float (it’s either a ball on an arm or a small cup attached to the fill valve).
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If it’s a ball float, gently bend the arm downward so the water shuts off about an inch below the top of the overflow tube.
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If it’s a cup-style float, adjust the screw or clip on the side of the fill valve to lower the water level.
Flush the toilet to test it — if the water stops flowing when it should, you’ve likely solved the problem.
Step 3: Inspect and Replace the Flapper
If adjusting the float doesn’t work, the flapper is the next suspect. Over time, the rubber can warp or decay, preventing a tight seal and letting water leak from the tank into the bowl.
To check it:
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Turn off the water supply (the valve is usually behind the toilet).
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Flush once to empty most of the water.
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Remove the flapper from the chain and unhook it from the overflow tube.
If it looks brittle, warped, or cracked, replace it — most hardware stores sell new ones for under $10. Attach the new flapper, reconnect the chain, and turn the water back on.
Step 4: Replace or Clean the Fill Valve
If your toilet still runs after replacing the flapper, the fill valve might be the issue. Debris or mineral buildup can cause it to stick open.
Try this first:
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Turn off the water supply and remove the fill valve cap.
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Rinse it under running water or soak it in vinegar to remove buildup.
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Reassemble and test.
If cleaning doesn’t work, replace the fill valve — it’s another easy DIY part that costs around $15 and installs in about 10 minutes using basic tools.
Step 5: Test and Fine-Tune
Turn the water back on and let the tank fill completely. Flush a few times to ensure everything works properly. Adjust the float height if needed so the water stops just below the overflow tube. Replace the tank lid once you’re satisfied.
Quick Recap
✅ Most common causes: Flapper leak or float set too high
✅ Tools you’ll need: Sponge, pliers, towel, adjustable wrench (maybe)
✅ Cost: Usually under $20
✅ Time required: 10–15 minutes
Final Thoughts
A running toilet is one of those household issues that seems intimidating but is actually simple to fix. With a few adjustments and inexpensive parts, you can stop the constant water flow, lower your bill, and feel pretty handy in the process.
So next time you hear that telltale trickle, don’t call the plumber — grab a wrench and take care of it yourself in minutes.
