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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- Adjustable pliers 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 Denver, tap water is moderate (80–150 ppm). Denver's water is moderately hard, sourced from snowmelt and groundwater. Scale buildup is noticeable but less severe than in hard-water metros. Water treatment varies by neighborhood.
Plumbers in Denver typically charge $110–170/hr. Most homeowners budget $800–2,500 for common repairs like fixture replacement, drain clearing, or valve repairs.
Colorado requires state licensing for plumbers. Denver requires permits. Homeowner exemptions limited to minor repairs.
Mix of pre-1950s and post-1970s construction. Older homes may have galvanized piping. Freeze-thaw cycles cause burst risk; insulation and heat tape are common. High altitude means lower boiling/freezing points affect equipment. Copper and PEX are standard in newer homes.
Denver winters regularly bring freezing temperatures. Pipe freeze risk is real, especially in older homes with uninsulated exterior walls. Heat tape and foam insulation on exposed pipes are worthwhile investments. Know where your main water shutoff is before winter.
DIY in Denver: Denver's moderate licensing and outdoor-focused culture support DIY repairs. Freeze-thaw maintenance and seasonal winterization are common homeowner tasks. High altitude knowledge is helpful. Most people hire professionals for electrical and HVAC work.
- 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 Denver.
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