Problem Overview
A toilet that won’t stop running can become quite costly. Most households lose hundreds of gallons of water per week from a single faulty toilet, and the cause is almost always something inside the tank. The flapper, the fill valve, or the float arm are the usual suspects. Knowing which one is misbehaving makes the fix straightforward.
Tools Needed
- Adjustable wrench
- Replacement flapper (match to your toilet model)
- Replacement fill valve (if needed)
- Rubber gloves
- Towels or a small bucket
- Food coloring (optional, for leak testing)
Step-by-Step Instructions
- Remove the tank lid and listen.
Set the lid aside carefully. Watch the water level. If it’s spilling into the overflow tube, the float is set too high. If the water level looks normal but the toilet still runs, the flapper is likely the culprit.
- Test the flapper.
Press down on the flapper with your finger. If the running stops immediately, the flapper is worn out and needs to be replaced. Add a few drops of food coloring to the tank and wait 10 minutes before flushing for a quick visual confirmation. The color appearing in the bowl confirms a leaking flapper.
- Replace the flapper.
Turn off the water supply valve at the base of the toilet. Flush to drain the tank. Unhook the old flapper from the overflow tube pegs and disconnect the chain from the flush handle arm. Snap the new flapper into place, reconnect the chain with about half an inch of slack, and turn the water back on.
- Adjust the float.
If water keeps rising to the overflow tube, the float needs to be lowered. On a ball float, bend the arm down slightly or turn the adjustment screw counterclockwise. On a cup float, pinch the clip and slide it down the fill valve shaft. The water level should sit about one inch below the top of the overflow tube.
- Inspect the fill valve.
If adjusting the float doesn’t solve it, the fill valve may be worn. Turn off the water supply, flush the tank, and follow the manufacturer’s instructions to replace the fill valve. Most replacements take under 30 minutes with basic tools.
- Turn the water back on and test.
Let the tank fill completely, then flush once. Watch and listen for another full minute. No running water means the job is done.
Safety Warnings
- Always turn off the water supply valve before working inside the tank.
- Avoid overtightening plastic components. Cracks in the tank are costly to repair.
- Keep towels nearby. Residual water in the tank will spill when you work on internal parts.
When to Call a Professional
Running toilets often point to deeper plumbing problems. If you’ve replaced the flapper and fill valve and the toilet still runs, there may be a crack in the tank, a faulty shutoff valve, or a supply line issue worth having a licensed plumber assess.
Our team at Sweetwater Plumbing has handled countless toilet and plumbing repairs across Ontario and the Inland Empire. We’re licensed, insured, and ready to take the guesswork out of stubborn plumbing problems.
Contact Sweetwater Plumbing and get the problem solved right.