Toilet Running Constantly? Here Is What Is Wrong and How Much It Costs to Fix
That hissing sound from your toilet is costing you money — up to $50/month in wasted water. Here's what's wrong and whether it's a DIY fix or a plumber job.
A constantly running toilet — that hissing or trickling sound that never quite stops — can waste 200 litres of water per day. At GTA water rates, that is roughly $30–$60 per month added to your water bill. The good news: it is almost always one of three things, and all three are fixable.
The Three Causes of a Running Toilet
1. Worn Flapper
The flapper is the rubber seal at the bottom of the tank that closes after each flush. Over time, rubber degrades, warps, or develops mineral buildup that prevents a tight seal. Water continuously leaks from the tank into the bowl — hence the running sound.
How to test: Put a few drops of food colouring in the tank. Wait 10 minutes without flushing. If colour appears in the bowl, the flapper is leaking.
DIY or plumber? A flapper replacement is a $5–$15 part and a 15-minute DIY job. If you are comfortable with basic hardware, do it yourself.
2. Faulty Fill Valve (Ballcock)
The fill valve refills the tank after each flush and shuts off when the water reaches the correct level. When it fails, water either overfills and runs into the overflow tube, or the valve never fully closes and water trickles continuously.
How to test: Check the overflow tube in the centre of the tank. If water is flowing over the top, the fill valve is set too high or is failing.
DIY or plumber? Fill valve replacement is manageable for handy homeowners — parts cost $15–$30. However, if you have older valve types or mineral buildup on the supply line, a plumber will save you frustration.
3. Worn Flush Valve Seat
If the flapper looks fine but water still leaks through, the seat the flapper rests on may be pitted or corroded. A damaged seat prevents any flapper from sealing properly. This typically requires replacing the flush valve assembly — a more involved job.
What Does a Plumber Charge for This?
- Flapper replacement only: $100–$160 (labour + part)
- Fill valve replacement: $130–$200
- Full internal rebuild (flapper + fill valve + flush valve): $180–$300
- Full toilet replacement: $400–$700+ depending on the model
When to Just Replace the Toilet
If your toilet is 20+ years old and has had multiple repairs, a new WaterSense-certified toilet (4.8 litres per flush) can pay for itself in water savings within a few years — and Toronto offers rebates for high-efficiency toilet replacements.
Call Proper Plumbing GTA for a flat-rate toilet repair or replacement: 647 206 3327
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