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How to Fix a Running Toilet

easyHome Repair30-60 minutes

Safety Warnings

  • Ensure the water is completely shut off at the angle stop before disconnecting hoses to avoid flooding.
  • Handle the toilet tank lid carefully as porcelain is fragile and can crack or break easily.

Tools Needed

Channel locks — Standard adjustable
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Sponge or Wet Vac — For removing remaining water from tank
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Materials

Replacement Flapper — Model specific to toilet(1)
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Replacement Fill Valve — Standard universal(1)
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Towel — Absorbent(1)
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Steps

1
Shut off the water using the angle stop valve located under the toilet and remove the tank lid, setting it aside safely.
Tip: If using an old-style angle stop, turn it slowly to ensure a full shut-off.
2
Place a towel under the tank and loosen the supply line to disconnect it, allowing any trapped water in the fill valve to drain.
Tip: Pull the hose over out of the way so it doesn't interfere with your work.
3
Inspect the flapper for cracks or nicks. If damaged, unhook it from the handle and snap in a new, compatible replacement flapper.
Tip: Ensure the new flapper reaches the top to ensure the toilet flushes properly.
4
If the flapper is fine, disassemble the fill valve by lifting and turning it to access the diaphragm valve.
Tip: Check for debris inside the valve.
5
Clean the diaphragm valve with soapy water and rinse it thoroughly. Reassemble the valve exactly as it was taken apart.
Tip: You can briefly crack the angle stop open to flush out any remaining trash in the valve.
6
If cleaning the diaphragm doesn't stop the running, remove the old fill valve entirely and install a new one, ensuring the rubber washer is on the bottom.
Tip: Use a sponge or wet vac to remove the remaining water from the bottom of the tank before pulling the valve.
7
Adjust the float on the new fill valve so the water level stops approximately a half-inch to an inch below the overflow tube.
Tip: If the old valve height worked well, use it as a reference for the new one.
8
Reconnect the supply line to the angle stop, tighten the nut, and turn the water back on to test the fill level.
Tip: Snug the connection well to prevent leaks.
9
Carefully place the tank lid back on the toilet once the water has reached the proper level and stopped running.

Pro Tips

  • Always verify that replacement parts are specifically designed for your toilet model.
  • Using a towel under the tank prevents water damage to your flooring during the repair.

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