Why Does My Toilet Keep Running?
Need help? See our Toilet Repair in the South Bay service page.
A toilet that keeps running after you flush is not just annoying. It can waste hundreds of gallons of water a day, and that shows up on your water bill fast. The good news: most running toilets have one of three causes, and all three are easy to check.
1. Start by lifting the tank lid
Flush once and watch what happens inside the tank. You are looking for three parts: the flapper (the rubber disc at the bottom), the fill valve (the tall valve on the left, connected to the water supply), and the overflow tube (the open pipe in the middle). Most running-toilet problems live in one of those three parts.
2. Check the flapper first
The flapper is the most common culprit. It seals the tank after a flush, and when it wears out, warps, or gets coated in mineral buildup, water leaks from the tank into the bowl nonstop, and the fill valve keeps refilling to compensate.
Test it this way: put a few drops of food coloring in the tank, wait 20 minutes without flushing, and check the bowl. If the bowl water is colored, the flapper is leaking. A replacement flapper costs a few dollars at any hardware store and usually just unhooks from two pegs and clips back on. Bring the old one with you so the size matches.
3. Check the chain and the water level
If the flapper looks fine, check the chain. It should have about half an inch of slack. A chain that is too short holds the flapper slightly open. A chain that is too long can tangle under the flapper and hold it open the same way.
Next, check the water level. It should sit about an inch below the top of the overflow tube. If it is higher, water is draining down the tube constantly. Lower it by adjusting the fill valve: turn the screw or slide the clip on the valve until the level drops to the right height.
4. Check the fill valve
If the flapper and chain are fine and the water level is right, the fill valve itself may be worn out. Signs: the valve hisses, it refills slowly, or it never fully shuts off. A fill valve replacement is a bigger job than a flapper, but it is still a standard repair, and it comes with instructions in the box.
5. When to call a plumber
Call if you have tried the flapper, chain, and water level and the toilet still runs, if the fill valve needs replacing and you are not comfortable shutting off the water and draining the tank, or if the toilet is also rocking, leaking at the base, or backing up. A leak at the base is a different problem, usually a failed wax ring, and it needs attention before it damages the floor.
South Bay Plumbing Pros is available 24/7 across San Jose, Sunnyvale, Cupertino, Mountain View, Campbell, Los Gatos, Menlo Park, and Santa Clara. Call (669) 308-4516 any time, day or night.
FAQ
How much water does a running toilet waste?
A toilet with a leaking flapper can waste 200 gallons or more per day, depending on how bad the leak is. That is why a running toilet is worth fixing the same week you notice it.
Is a running toilet an emergency?
It is not a flooding emergency, but it is urgent for your water bill. If the toilet is also overflowing or leaking onto the floor, shut off the water at the valve behind the toilet and call right away.
Can I just jiggle the handle and leave it?
Jiggling the handle reseats a flapper that is slightly off, and it works as a stopgap. If you have to do it after every flush, the flapper or chain needs replacing.
Why does my toilet run every few minutes without being flushed?
That is called phantom flushing. The tank is slowly leaking into the bowl, the water level drops, and the fill valve tops it up. It is almost always the flapper.
