Why Your Westminster Toilet Keeps Running — Flapper, Fill Valve, or Something Worse?

By Westminster Leak Repair Pros Team · Westminster, CO

A Westminster toilet that keeps running after flushing is doing one of three things: seeping past the flapper, cycling because the fill valve cannot shut off, or overflowing into the overflow tube. Each has a different cause, a different repair cost, and a different urgency level. Westminster's 7-to-8-grain-per-gallon Clear Creek water from Standley Lake contributes to all three failure modes, but at different timescales and through different mechanisms.

Cause 1: Flapper not sealing (ghost flush)

The flapper is the rubber disk at the bottom of a Westminster toilet tank that seals the tank opening and holds water for the next flush. In Westminster's Clear Creek water, mineral scale from the city's Standley Lake supply deposits on the flapper seating ring over 5 to 15 years, producing an irregular surface that prevents the flapper from seating flat against the valve seat. Water seeps continuously through the gap between the scaled seating ring and the flapper face, dropping the tank water level slowly below the fill trigger threshold.

The fill valve then activates briefly to top up the tank, runs for 5 to 15 seconds, shuts off, and the cycle repeats. This is the "ghost flush" that Westminster homeowners describe as the toilet running for a few seconds periodically throughout the day. A food coloring test confirms flapper failure: put a few drops of food coloring in the tank. If color appears in the bowl within 10 to 15 minutes without flushing, the flapper is failing to seal.

Westminster flapper failures typically produce 200 to 400 gallons per day of water waste, which adds $15 to $30 to the City of Westminster monthly water bill. The repair is a flapper replacement using a flapper with a silicone or hard plastic seating ring rather than a standard rubber flapper, since the harder material resists the mineral scaling that caused the original failure. Cost: $20 to $80 with parts and labor in Westminster.

Cause 2: Fill valve failure (constant running)

A Westminster toilet fill valve that runs continuously without stopping has one of two problems: the float arm is set too high so the water level never rises to the shutoff point, or the fill valve seat itself has mineral scale preventing the valve from seating closed. The first problem shows up as a toilet where the water level in the tank is at or above the overflow tube and water is trickling into the bowl through the overflow. The water level adjustment is a float arm bend or a float screw turn. The second problem shows up as a fill valve that runs even when the float is manually held at the shutoff position, indicating the valve internals have failed from Westminster's mineral load.

Fill valve replacements in Westminster use units with stainless steel or ceramic internal seating surfaces rather than rubber seats, since the harder materials resist scale bonding in Westminster's 7-to-8-GPG environment. A fill valve replacement in Westminster runs $40 to $120 for parts and labor. Westminster homeowners who have replaced the flapper already but still have a running toilet almost always need the fill valve replaced as the next step.

Cause 3: Toilet overflow tube running (less common, more urgent)

A Westminster toilet where water is continuously running into the overflow tube, the vertical standpipe in the center of the tank, has a fill valve set too high for the current tank configuration or a float that is not shutting off the fill valve at the correct water level. Water that runs continuously through the overflow tube in a Westminster toilet is wasting water at a higher rate than flapper seepage because the full tank fill volume is draining rather than a slow seep. A toilet overflow running continuously in a Westminster home wastes 1.5 to 3.0 gallons per minute, depending on the fill valve flow rate. At Westminster's water rates, that is $90 to $180 per day in water cost.

The fix is adjusting the fill valve float arm or replacement screw to lower the shutoff water level below the overflow tube opening. If the float adjustment does not resolve the overflow, the fill valve is failing to respond to the float position, which means the fill valve needs replacement. This repair is urgent in Westminster given the water waste volume involved.

When Is a Westminster Running Toilet "Something Worse"?

A running toilet that does not respond to flapper and fill valve replacement, or that is running from a crack in the tank or the connection between the tank and the bowl, indicates a structural failure rather than a component failure. Tank cracks in Westminster toilets are typically caused by freeze-thaw stress in unheated spaces or physical impact. A crack in a porcelain toilet tank cannot be repaired reliably; the tank or the full toilet unit requires replacement.

A running toilet that is accompanied by water at the base of the toilet after flushing, rather than in the tank, indicates a wax ring failure or a cracked toilet base rather than a running tank situation. The two are distinct problems that share some surface symptoms but have different repair approaches. Our toilet leak service in Westminster covers the full assessment to distinguish tank failures from base seal failures before parts are ordered.

Westminster Leak Repair Pros provides toilet repair throughout Westminster, including Walnut Grove Westminster, Cotton Creek, and all Westminster neighborhoods. The City of Westminster's 2026 Drought Watch makes toilet water conservation more meaningful than usual: a running Westminster toilet wasting 300 gallons per day during a period of reduced Standley Lake snowpack inflow is a genuine community water conservation issue. Call (303) 552-3896 to schedule a toilet assessment.