That phantom flush — your toilet running for a few seconds every hour — is more than annoying. It’s wasting water and quietly inflating your utility bill.
As a local Twin Cities plumber, I get calls about this all the time, especially in older homes in Minneapolis and St. Paul. The good news? An occasionally running toilet is almost always a DIY-fixable problem with a $5 part.
The most common culprit: the flapper!
You will need to measure the old flapper – 3″ is a common size. All home improvement stores sell flappers – Click here for a universal flapper recommendation.
Inside your toilet tank, a rubber flapper seals the opening between the tank and bowl. Over time it warps, hardens, or collects mineral buildup — especially common here in the Twin Cities where we have moderately hard water. When it doesn’t seal properly, water slowly leaks into the bowl, triggering the fill valve to refill the tank.
Quick test: Drop a few drops of food coloring into your tank. Don’t flush. Wait 10 minutes — if color appears in the bowl, your flapper is leaking.
First, turn off the water supply to the toilet. If your shut off valve is stuck, you may need to call us to replace the shut off valve. Then, flush the toilet to empty the tank. Remove old flapper – if necessary, you may need to cut it off.
Then, clip on the new flapper and attach the chain to the flapper stack with just a little slack.
If a new flapper doesn’t solve it, check the float. The float controls the water level — if it’s set too high, water spills into the overflow tube constantly. Bend the float arm down slightly or adjust the float clip until the water sits about an inch below the overflow tube.
A worn fill valve is the third possibility. If you hear hissing even with a good flapper, the fill valve itself may need replacing — still a simple repair, Rick is holding a new fill valve in this image.
You can find detailed instructions on installing a new fill valve from Fluidmaster here. If you’re not comfortable doing this yourself, give us a call.
While you’re replacing all of the innards of your toilet, don’t forget the water supply line to your toilet. Over time, the braided stainless water supply line can harden up and need replacing.
A dedicated toilet supply line can be purchased at a hardware or home improvement store. The intake line comes pre-cut, with lock nuts on both ends, and is easy to install while the water is shut off.
Now, turn the water on, watch the tank fill, and try flushing. You may need some adjustments to the flapper chain, the fill valve, or other components. Check for any leaks or drips all around the toilet, and tighten up where needed.
Test your work by putting food dye in the tank, to make sure you don’t still see leaks from the tank to the bowl.
To summarize:
- Test for leaks using food dye in the toilet tank.
- Purchase parts from your hardware or home improvement store:
- Universal toilet flapper
- Universal fill valve
- Braided stainless toilet water supply line
Contact Jake the Plumber if you want us to come out and diagnose and fix your toilet.
