Let’s be real: a running toilet is more than just an annoying sound. It’s the sound of money literally going down the drain. That constant hiss or trickle can waste hundreds of gallons of water a day, which shows up as a nasty surprise on your water bill. Before you panic and call for backup, know this—most running toilets are caused by one of three simple, fixable problems. Here’s your DIY detective guide.

First, play detective. Pop the lid off your tank (carefully, please!) and take a listen and a look. Is there a constant, gentle stream of water flowing into the bowl? Or is the tank refilling every few minutes on its own? This clue points to the culprit.

The Usual Suspects:

• The Wimpy Flapper: This is the rubber stopper at the bottom of the tank. Over time, it gets warped or covered in mineral gunk, preventing a tight seal. Water constantly leaks from the tank into the bowl. Give it a feel. Is it slimy or cracked? Replacing a flapper is a $10, 5-minute fix. Just make sure you get the right model for your toilet.
• The Misbehaving Fill Valve: That’s the tall mechanism on the left. If you hear a constant hiss or see water running down the overflow tube (the tall open pipe in the middle), the fill valve’s internal seal is worn out. You can try cleaning it, but a new fill valve assembly is often the permanent solution.
• The Out-of-Whack Float: This is the ball or cup that tells the tank when it’s full. If it’s set too high, water goes into the overflow tube. If it’s a ball float, gently bend the arm down a bit. If it’s a cup, adjust the slide clip. The water line should be about an inch below the overflow tube’s top.

When to Wave the White Flag: If you’ve swapped the flapper, adjusted the float, and water is still staging a great escape, you might have a crack in the flush valve (the big plastic piece the flapper sits on) or a worn-out tank-to-bowl gasket. These are more involved repairs. This is when calling a pro saves you time, water, and a major headache.

Think of a little toilet maintenance as homeownership self-care. A silent toilet is a happy toilet—and a kind one to your wallet.