Why your toilet keeps running, and how to fix it
A toilet that keeps running almost always has one of two problems. Either the flapper at the bottom of the tank isn’t sealing and water is leaking into the bowl, or the water level is set too high and it’s spilling into the overflow tube. Take the tank lid off and look. Both fixes use cheap parts, and most people can handle them without a plumber.
Lift the lid and look
Set the tank lid down somewhere flat, on a towel if you’ve got one. They’re heavy and they crack.
Now watch the water. There’s a tall open pipe in the middle of the tank called the overflow tube. If water is running over the top of it, the water level is too high, and you can skip down to the float section. If the level is below the overflow tube and the tank still keeps refilling, water is leaking past the flapper into the bowl.
While you’re in there, find the small flexible tube coming off the fill valve. It should clip onto the top of the overflow tube and drip in from above. If it’s been pushed down inside the overflow tube below the water line, it can siphon water out of the tank nonstop. Pull it up and clip it back in place.
Is it the flapper?
The flapper is the rubber cap at the bottom of the tank. When you flush, the chain lifts it and water rushes into the bowl. When the tank empties, it drops back down and seals. Over time the rubber gets stiff and warped, and it stops sealing all the way.
Check the chain first. With the flapper closed, the chain should have a little slack, about half an inch. Too tight and it holds the flapper open a crack. Too loose and the extra chain can get caught under the flapper.
If you’re not sure the flapper is leaking, do a dye test. Put a few drops of food coloring in the tank and don’t flush. Wait 15 or 20 minutes. If color shows up in the bowl, the flapper’s leaking.
How to replace a flapper
- Turn off the supply valve behind the toilet. Turn it clockwise until it stops.
- Flush and hold the handle down to drain as much of the tank as you can.
- Unhook the chain from the handle arm.
- Pop the flapper’s ears off the pegs on the sides of the overflow tube. Some flappers slide on with a ring instead.
- Take the old one to the hardware store with you. Most flappers are 2 inch or 3 inch, and matching the old one saves you a second trip.
- Wipe off the rim the flapper sits on. Mineral buildup there can keep even a brand new flapper from sealing, and it’s more common if your water is on the hard side.
- Put the new flapper on, hook up the chain with a little slack, and turn the water back on.
Some toilets don’t have a flapper at all. They have a tall cylinder in the middle of the tank with a rubber seal at the bottom. Same idea, different part, so bring the old seal to the store.
How to adjust the float
If water is running into the overflow tube, the fill valve isn’t shutting off soon enough. The float is what tells it to stop. Lower the float and the water shuts off sooner.
- Most newer toilets have a float cup that rides up and down on the fill valve. There’s usually a long adjustment screw or a clip on the side. Turn the screw or slide the clip down to lower it.
- Older toilets have a ball on the end of a rod. Some have an adjustment screw where the rod meets the valve. On others, you gently bend the rod down a little.
Set it so the water stops about an inch below the top of the overflow tube, or at the water line mark if your tank has one. Flush and check again.
If the level is set right, the flapper’s sealing, and the tank still hisses or trickles, the fill valve itself is wearing out. Same goes if you lower the float and the water keeps rising anyway. Replacement fill valves are sold as universal kits that fit most toilets, and swapping one is a reasonable DIY job. You shut off the water, drain the tank, disconnect the supply line under the tank, and swap the valve. If that’s more than you want to take on, call us.
What’s ghost flushing?
That’s when the toilet refills for a few seconds on its own with nobody touching it, sometimes in the middle of the night. It’s a slow leak past the flapper. The tank level drops just enough to trip the fill valve, and it tops itself back off. Do the dye test, and if the color shows up, replace the flapper.
Why it’s worth fixing now
A running toilet can waste a lot of water, and it’ll show up on your bill. Don’t count on a leak adjustment to cover it, either. Huntsville Utilities can adjust a bill for a hidden or underground leak, but not for leaks you could see or hear, and a running toilet is one of those. The details change, so call them with questions about your bill. If it jumped and the toilets all check out, here’s how to check for a hidden leak.
Call a plumber if the tank is cracked, if there’s water on the floor around the toilet, or if you’ve replaced the flapper and the fill valve and it still runs. And watch the shutoff valve behind the toilet. Old ones seize up and sometimes start leaking when you turn them. If yours won’t budge, don’t force it. Give us a call.