What's actually causing this
Toilets run when water continuously trickles from the tank into the bowl. The two most common culprits are a worn-out flapper that doesn't seal properly, and a fill valve that's stuck open or set too high.
What you'll need
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- Toilet flapper kit Shop →
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Step-by-step fix
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1
Diagnose the problem
Lift the tank lid and add a few drops of food coloring. If color appears in the bowl within 10 minutes without flushing, the flapper is leaking.
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2
Turn off the water supply
Turn the shutoff valve behind the toilet clockwise. Flush once to empty the tank.
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3
Replace the flapper
Unhook the old flapper from the overflow tube pegs. Snap the new flapper in place and reconnect the chain — leave about half an inch of slack.
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4
Adjust the fill valve
If water is running over the overflow tube, the water level is too high. Adjust the float arm or float ball downward until the water sits 1 inch below the top of the overflow tube.
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5
Turn water back on and test
Slowly open the shutoff valve. Let the tank fill and listen for any continued running after the fill cycle completes.
In Chicago, tap water is very hard (280–350 ppm). Chicago's water is among the hardest in major U.S. cities, sourced from Lake Michigan. Heavy mineral deposits accumulate on fixtures and inside pipes. Water softeners are extremely common. Hard water accelerates water heater failure.
Plumbers in Chicago typically charge $110–180/hr. Most homeowners budget $800–2,500 for common repairs like fixture replacement, drain clearing, or valve repairs.
Illinois requires journeyman and master plumber licenses. Chicago requires city permits and inspections. Homeowner exemptions are limited to minor repairs on owner-occupied properties.
Pre-1950s homes commonly have galvanized steel piping with severe corrosion issues. Cast-iron drain stacks are typical and may need replacement. Many homes have had copper installed over decades. Water softener installation is almost universal.
DIY in Chicago: Chicago's licensing requirements are moderate. Homeowners can perform some plumbing and electrical work on their own homes, but city inspections are strict. Most people hire contractors for permits and anything beyond cosmetic repairs.
- The tank or bowl has visible cracks.
- The toilet rocks or is loose at the base — this may indicate a wax ring failure.
- Water appears on the floor around the base after flushing.
Let Uncle AI diagnose it first.
Describe the problem. Uncle AI asks the right questions and tells you exactly what's broken — and whether you should fix it yourself or call someone in Chicago.
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