Responsible Master Plumber · TX Master Plumber License M-41984
Quick answer
A running toilet is almost always caused by a worn flapper, a misadjusted float, or a failing fill valve in the tank. Most cases are fixable in a few minutes by reseating or replacing the flapper and adjusting the water level — here's how, and when to call a plumber.
Why does a toilet keep running?
A toilet runs when water keeps moving from the tank into the bowl (or down the overflow) instead of sealing off after a flush. Three parts cause nearly all of it: a worn or misaligned flapper (the rubber seal at the bottom of the tank), a float set too high so water spills into the overflow tube, or a failing fill valve that won't shut off. A running toilet isn't just annoying — it can quietly waste hundreds of gallons a day and inflate your water bill.
How do I fix a running toilet step by step?
- Take off the tank lid and watch a flush cycle so you can see what's not sealing.
- Check the flapper. If it's warped, stiff, or coated in mineral scale, it won't seal — clean it or replace it (an inexpensive, universal part).
- Check the chain. Too short and it holds the flapper open; too long and it gets trapped underneath. Adjust for a little slack.
- Set the water level. It should sit about an inch below the top of the overflow tube. Adjust the float down if water is spilling into the overflow.
- Test the fill valve. If water still runs after the above, the fill valve is likely worn and should be replaced.
Why does my toilet keep doing this in Central Texas?
If you replace the flapper and it fails again sooner than it should, blame the water. Our hard water leaves mineral scale on flappers and valve seats, breaking the seal faster than in soft-water regions. Whole-home softening extends the life of toilet parts — and every other fixture in the house.
When should I just call a plumber?
Call a pro if the toilet still runs after replacing the flapper and fill valve, if you see water on the floor or around the base (a possible wax-ring or supply-line issue), if the toilet rocks, or if you'd simply rather have it handled right the first time. Toilet repairs are one of our published flat-rate Essential Ten services — a known price, no dispatch fee, no guesswork.
Tried it and the toilet still runs?
Request a repair — toilet repairs are flat-rate through the Essential Ten. And if scale keeps wrecking your fixtures, ask about whole-home water treatment.
Key takeaways
- Most running toilets are a worn flapper, a too-high float, or a failing fill valve.
- You can fix the majority in minutes by reseating/replacing the flapper and setting the water level.
- Hard-water scale makes flappers fail faster in Central Texas — softening helps.
- Toilet repairs are flat-rate through the Essential Ten if you'd rather we handle it.
Frequently asked questions
- Is a running toilet an emergency?
- It's not an emergency, but it's not harmless either — a running toilet can waste hundreds of gallons a day and spike your water bill, so it's worth fixing promptly.
- How much does it cost to fix a running toilet?
- Toilet repairs are one of our published Essential Ten services at a flat $325, with no dispatch fee — so you know the price before we start.
- Why does my flapper keep failing?
- In Central Texas, hard-water mineral scale builds up on the flapper and valve seat and breaks the seal faster than normal. Whole-home softening makes flappers and other fixtures last much longer.
