After two decades as a master plumber here in Toronto, one of the most common issues I get called for is a toilet that just won’t stop running. It might seem minor at first—but trust me, it can waste hundreds of litres a day and quietly jack up your water bill.
If you’re dealing with a toilet that won’t shut up, here are the top 8 reasons I usually find—and how you can fix them yourself before picking up the phone.
1. The Flapper Isn’t Sealing Properly
What I see all the time: The rubber flapper at the bottom of the tank has worn out or warped, so water constantly leaks into the bowl.
What I recommend:
- Take the tank lid off and flush. Watch the flapper.
- If it doesn’t drop and seal completely, it’s likely the issue.
- Shut off the water (look for the valve behind the toilet), drain the tank, and unclip the old flapper.
- Clip on a new one—usually around $10 at Home Depot or Canadian Tire—and you’re back in business.
2. The Float Isn’t Doing Its Job
Sometimes the float—whether it’s a ball or vertical cylinder—fails to shut off the water when the tank is full.
Quick fix I’ve used dozens of times:
There’s often a little dial or adjustment screw near the top of the float mechanism.
- Turn it to lower the float slightly.
- The water should stop about 1–1.5 cm below the top of the overflow tube.
Problem solved.
3. Debris Inside the Fill Valve
I’ve seen this in Toronto homes with older plumbing or well water systems: grit or even tiny stones get stuck inside the fill valve.
What I’d do:
- Turn off the supply line.
- Remove the cap on the fill valve (usually press-and-twist).
- Rinse it out and put it back together.
You’d be surprised how often this tiny fix saves a service call.
4. Chain’s Too Tight (or Too Loose)
I always check the flush chain. If it’s too tight, it pulls the flapper up just enough to keep leaking. Too loose, and it gets caught underneath.
What to do:
- You want about ½ inch of slack.
- Try hooking the chain a link or two higher, or bending the flush arm slightly to relieve tension.
5. Overflow Tube Is Cracked or Misaligned
If water keeps flowing down the overflow tube, the tube may be cracked or sitting too high.
My approach:
- Shine a flashlight inside and inspect for cracks.
- If damaged, you’ll likely need to swap out the flush valve assembly—not a big job if you’re handy. Kits usually cost under $25.
6. Worn Seals and Gaskets
A lot of older toilets around the GTA have rubber gaskets that have dried out or cracked.
Here’s how I fix it:
- Shut off the water and flush to drain the tank.
- Carefully unbolt and lift off the tank.
- Replace the tank-to-bowl gasket and other seals (they come in a kit).
- Reassemble and test for leaks.
7. The Fill Valve Is Worn Out
Sometimes it’s just age. The diaphragm inside the fill valve wears down and can’t hold pressure.
Quick fix:
- Replace the fill valve completely—don’t waste time fiddling with a failing one.
- A universal replacement kit costs around $15–$20, and you can install it with a basic wrench.
8. Your Water Pressure Is Too High
Toronto homes with high municipal pressure or booster pumps can overwhelm toilet valves, especially at night.
If I suspect this:
- I’ll test the pressure—anything over 80 psi is a problem.
- You can install a pressure regulator on the toilet’s line or have one added at the main for the whole house.
Pro Tip from a Pro
If you don’t want to waste time troubleshooting each part, just buy a toilet repair kit. It comes with a flapper, fill valve, seals, and everything you need. Match it to your toilet brand (or go universal), and you’ll get a full refresh in one go.
Need Professional Help?
If you’ve tried the fixes above and your toilet is still acting up—or you’d rather skip the hassle altogether—Plumber To Your Door is here to help.
We offer fast, reliable toilet repair services across Toronto, with:
✔️ Same-day service
✔️ A solid 12-month warranty on all repairs
✔️ And over 20 years of plumbing experience
Give us a call and we’ll get your toilet sorted—properly and professionally.
About the Author:
George G. is the owner of Plumber To Your Door and a master plumber with over 20 years of experience in residential plumbing across Toronto.