Toilet Keeps Losing Water: Fix It Now

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Quick answer
Confirm the symptom
Tools and prep
Step-by-step troubleshooting
Common causes table
Parts matching
When to call a pro
FAQ
Related guides

Quick answer

Your toilet likely has a faulty flapper or fill valve. Turn off the water supply, check the flapper chain, and adjust or replace if needed. If the issue continues, replace the fill valve.

Confirm the symptom

Water is constantly running into the toilet bowl
You hear a continuous hissing or trickling sound from the tank
The water level in the tank drops over time
The toilet makes a gurgling noise after flushing

Tools and prep

Adjustable wrench
Screwdrivers (flathead and Phillips)
Plumber's putty or silicone sealant
Replacement flapper or fill valve
Turn off the water supply to the toilet
Place a towel or bucket under the toilet to catch water

Step-by-step troubleshooting

Turn Off Water Supply
Do: Locate the water shut-off valve near the base of the toilet and turn it clockwise to shut off the water.
Observe: Water stops flowing into the tank.
Means: You can now safely work on the toilet without more water entering.
Next: Drain the tank.
Drain the Tank
Do: Flush the toilet to drain as much water as possible. Use a sponge or towel to soak up remaining water.
Observe: Tank is mostly empty and no water is dripping.
Means: The tank is ready for inspection.
Next: Inspect the flapper and chain.
Inspect the Flapper and Chain
Do: Look at the flapper (rubber valve at the bottom of the tank) and check if it's worn, cracked, or not sealing properly. Ensure the chain is not too tight or tangled.
Observe: Flapper is damaged or chain is misadjusted.
Means: A faulty flapper or chain is likely causing the water loss.
Next: Adjust or replace the flapper.
Adjust or Replace the Flapper
Do: If the chain is too tight, loosen it. If the flapper is damaged, remove it by detaching the chain and lifting it off. Install a new flapper following the manufacturer's instructions.
Observe: Flapper seals tightly against the valve and chain has some slack.
Means: The flapper should now prevent water from leaking into the bowl.
Next: Test the toilet.
Test the Toilet
Do: Turn the water supply back on and let the tank refill. Flush the toilet and observe for any water loss or unusual sounds.
Observe: Water level remains steady and no running water is heard.
Means: The issue is resolved.
Next: Monitor the toilet over the next few days.
Check the Fill Valve
Do: If the problem persists, inspect the fill valve (the tall tube near the back of the tank). Adjust the float or replace the fill valve if it's faulty.
Observe: Water level in the tank is correct and the fill valve shuts off properly.
Means: A faulty fill valve was the cause of the water loss.
Next: Monitor the toilet for further issues.

Common causes

Cause	Likelihood	Difficulty	Part often needed
Faulty Flapper The flapper doesn't seal properly, allowing water to leak into the bowl.	Common	Easy	Toilet Flapper
Misadjusted Chain A chain that's too tight or too loose can prevent the flapper from sealing correctly.	Common	Easy	Toilet Chain
Worn Out Fill Valve The fill valve may not shut off properly, causing continuous water flow.	Common	Easy–Medium	Fill Valve
Cracked Tank or Bowl Cracks can cause water to leak out of the toilet.	Rare	Hard	Toilet Replacement
Faulty Float Ball or Cup A faulty float can cause the fill valve to overfill or not shut off.	Sometimes	Easy–Medium	Float Assembly
Clogged Overflow Tube A clog in the overflow tube can cause water to continuously run.	Sometimes	Easy	Plunger or Cleaning Tools

Parts matching

Common parts needed to fix a toilet that keeps losing water:

Toilet Flapper: Replaces the rubber valve that seals the tank.
Fill Valve: Controls the water level in the tank.
Toilet Chain: Connects the flapper to the flush handle.
Float Assembly: Regulates the water level in the tank.
Plumber's Putty: Seals small leaks around the toilet base.

Purchase parts that match your toilet model for the best fit and performance.

When to call a professional

Water continues to run after replacing the flapper and fill valve.
You notice water damage or mold around the toilet base.
The toilet tank or bowl is cracked and leaking.
You're unsure about the correct part to replace or how to install it.
The problem persists for more than a day after attempting fixes.

FAQ

How do I know if my toilet flapper is bad?

If the flapper is cracked, warped, or doesn't seal properly, it's likely bad. You may also hear water running into the bowl when the toilet isn't being used.

Can a running toilet increase my water bill?

Yes, a running toilet can waste hundreds of gallons of water per day, significantly increasing your water bill.

How often should I replace my toilet flapper?

Toilet flappers typically last 1–5 years. Replace them if you notice leaks or if the toilet starts running continuously.

What if adjusting the chain doesn't fix the problem?

If adjusting the chain doesn't work, the flapper itself may be damaged and need replacement. If the issue continues, check the fill valve or consult a professional.