Quick Answer:
If the tank refills when you haven’t touched the handle, the first thing to check is how the small refill tube is routed. The tube should sit clipped above the overflow pipe, not shoved down into it. If it’s pushed inside the overflow, it can siphon or feed water into the bowl. If repositioning the tube doesn’t stop the refill, the fill valve or a leaking flapper may be the cause.
Why This Happens
- The refill tube is meant to add a small amount of water to the bowl after a flush. If it’s inserted into the overflow opening it can cause water to flow into the bowl continuously or intermittently.
- A worn or misadjusted fill valve can let water trickle into the tank and over the overflow, triggering repeated refills even with the tube routed correctly.
- A leaking flapper lets tank water escape into the bowl, which raises the water level in the bowl and prompts the fill valve to run. If you recently had work done or a pressure event, see Phantom flushes; if you suspect an outside pressure cause, see Random refills.
Step-by-Step What to Do
1. Observe the tank
- Carefully lift the tank lid and set it aside on a towel or safe surface.
- Watch the tank while the toilet is idle. Note where the small refill tube ends and whether water is flowing from it into the overflow.
2. Inspect refill tube routing
- Look for the refill tube that runs from the fill valve to the overflow pipe. It should be clipped so the open end points into the overflow throat but does not extend inside the opening.
- If the tube is pushed down into the overflow, pull it up so the end sits above the top of the overflow pipe and secure it with the clip on the fill valve body.
3. Clip above the overflow rather than inside it
- Use the plastic clip that came with the fill valve or a small plastic tie to hold the refill tube above the overflow. The tube should be close enough to direct water into the overflow area but not inserted into the hole where it can siphon.
- After repositioning, flush once and watch — the refill tube should only run briefly to refill the bowl and then stop.
4. Test for other leaks
- To check the flapper, add a few drops of food coloring to the tank (do not use chemical dyes). Wait 10–30 minutes without flushing. If colored water appears in the bowl, the flapper is leaking and needs replacement.
- If the flapper is good and the tube is routed correctly but the fill valve keeps running, the fill valve may be worn and should be adjusted or replaced.
5. Temporary shut-off if continuous refill wastes water
- If water continues to run and you need a quick fix, turn the shut-off valve at the toilet clockwise to stop the water supply until you can make repairs or call help.
What Not to Do
- Don’t leave the refill tube inserted into the overflow hole — that promotes siphoning or continuous flow.
- Don’t ignore ongoing water flow; prolonged running wastes water and can raise your bill.
- Don’t delay calling a plumber if routing is unclear or you can’t stop the refill after the basic checks.
When to Call a Professional
- After you reposition the refill tube and check the flapper, if the toilet still refills on its own, call a plumber. Persistent running often means the fill valve needs replacement or a more detailed diagnosis.
- Call a pro if you’re unsure how the refill tube should be clipped, if parts are brittle or broken, or if tightening or adjusting the fill valve creates leaks.
- Also call if you turn off the supply and the leak continues or if you notice unusual noises or repeated refilling tied to external water system events.
Safety Notes
- Place the tank lid on a soft towel while you work to avoid chipping or cracking porcelain.
- Turn the shut-off valve off before doing in-depth work that requires draining the tank. Flush once to empty the tank before touching internal parts.
- Avoid forcing plastic clips or brass parts; they can break. Replace damaged clips rather than trying to jury-rig them with metal that might corrode.
Common Homeowner Questions
- Is the refill tube supposed to be inside the overflow?
Short answer: No. It should be clipped above the overflow, not inserted into it. - Will a refill tube cause siphoning?
Short answer: Yes, if it’s pushed into the overflow hole it can siphon or continuously feed water into the bowl. - Can I fix this myself?
Short answer: Often yes — reposition the tube, clip it above the overflow, and test the flapper. Call a plumber if the problem persists or parts are damaged.