How to Stop a Running Toilet (Fast!)

That constant water sound isn't just annoying—it's money going down the drain.

I'm Justin Sims, and if you're reading this at midnight because that toilet won't shut up, I feel you. A running toilet is one of those problems that seems minor until you're lying awake listening to it, wondering how much your water bill is going to be.

The good news: this is usually fixable in minutes, and you might not even need a plumber. Let me walk you through it.

Stop the Running Right Now (30-Second Fix)

First, let's just make it stop:

1. **Take the lid off the tank** (the rectangular part on top—it lifts right off)
2. **Look for the rubber flapper** at the bottom of the tank
3. **Press down on it firmly**

If the running stops when you push the flapper, you've found your culprit. If it doesn't, look for the float (the ball or cylinder that rises with the water level) and push it down. Did the running stop?

Great. Now let's figure out a permanent fix.

What's Actually Happening Inside Your Toilet

Your toilet tank is simpler than you might think. Here's the basic flow:

1. You flush → the flapper lifts → water rushes into the bowl
2. The flapper closes → tank refills
3. A float rises with the water level
4. When the float reaches a certain height, it tells the fill valve to stop
5. Everything goes quiet until the next flush

A running toilet means something in this chain isn't working. Usually it's one of three things:

Problem #1: The Flapper (Most Common)

The flapper is that rubber piece at the bottom of the tank. When you flush, it lifts up to let water flow out. Then it's supposed to seal shut.

Signs it's the flapper:

• You hear water trickling into the bowl constantly
• If you put food coloring in the tank, it shows up in the bowl without flushing
• The rubber feels stiff, warped, or has visible deterioration

The fix:

Flappers are universal, cost about $5, and take 2 minutes to replace:

1. Turn off the water supply (the valve behind/below the toilet)
2. Flush to empty the tank
3. Unhook the old flapper from the overflow tube and chain
4. Hook on the new flapper
5. Adjust the chain so there's about 1/2" of slack
6. Turn water back on and test

That's it. You just saved yourself a service call.

Problem #2: The Float Is Set Too High

If the water level in your tank is too high, it spills into the overflow tube (that tall pipe in the center of the tank). That's why it sounds like it's constantly running—because it is.

Signs it's the float:

• Water level in the tank is at or above the overflow tube
• You can see water trickling into the overflow tube

The fix:

For a ball float (old style—ball on a metal arm):

• Bend the arm down slightly
• Or adjust the screw at the fill valve to lower the float

For a cylinder float (newer style—slides up and down a column):

• Look for an adjustment screw or clip on the float
• Slide or adjust it lower
• The water level should be about 1 inch below the top of the overflow tube

Problem #3: The Fill Valve Is Worn Out

The fill valve is the tall mechanism on the left side of the tank. It's what controls the water coming in.

Signs it's the fill valve:

• Water doesn't shut off no matter what you do with the float
• You hear hissing or whistling
• The valve is obviously old or damaged

The fix:

Fill valves are replaceable, but this one's a bit more involved:

1. Turn off water supply and flush the tank
2. Sponge out remaining water
3. Disconnect the water supply line (have a towel ready)
4. Unscrew the locknut under the tank
5. Remove old valve, install new one
6. Reconnect and adjust

If you're comfortable with basic DIY, this is doable. If not, this is a quick job for a plumber and relatively inexpensive.

The Water (and Money) You're Losing

A running toilet can waste 200+ gallons per day. At Austin water rates, that's adding $50-100+ to your monthly bill. Over a year? You could be wasting $600-1200 on water that goes straight down the drain.

Plus, if you're on a septic system (common in the Hill Country), you're filling your tank faster, which means more frequent pumping.

When to Call a Plumber

Most running toilets are DIY-fixable, but call us if:

• You've replaced the flapper and fill valve and it still runs
• There's water leaking onto the floor (not the same problem)
• The tank has cracks
• The toilet rocks or feels unstable
• You're just not comfortable doing this yourself

No judgment on that last one. Some folks love a DIY project; others would rather watch football. We're here either way.

A Quick Toilet Health Check

While you've got the lid off, here are some other things to look for:

**Rust or corrosion:** Usually means hard water buildup. Consider your water quality.

**Cracked tank:** Rare, but if you see it, the whole toilet needs replacing.

**Ancient hardware:** If everything looks like it's from 1985, consider replacing all the tank internals at once. A $25 kit can give you another decade of trouble-free flushing.

The Bottom Line

A running toilet is usually one of the simplest plumbing fixes. Nine times out of ten, it's a $5 flapper or a quick float adjustment. The supplies are at any hardware store, and you don't need any special tools.

But if you're not the DIY type, or if you've tried everything and it's still running, we're happy to come take a look. No job too small.

**Can't figure it out?** Give us a call at (512) 665-0250 — we give a 💩 about even the little stuff.

*Justin Sims is a Master Plumber and owner of SimsCo Mechanical & Plumbing, serving Westlake Hills, Bee Cave, Lake Travis, and Dripping Springs.*