How to Fix a Toilet That Won't Stop Running

A toilet that runs continuously, or keeps refilling on its own every few minutes, isn't just an odd noise you learn to live with. Depending on how bad it is, a running toilet can waste anywhere from tens to hundreds of gallons a day, which shows up as a noticeably higher water bill by the end of the month even though nothing about your habits changed. The fix is usually one of two parts, and both are within reach for most homeowners.

Step 1: Take the tank lid off safely

Lift the tank lid straight up with both hands and set it somewhere padded, like a folded towel, rather than directly on a hard tile floor. Tank lids are heavier and more fragile than they look, and a chip or crack means an expensive replacement for a part that's otherwise fine.

Step 2: Watch what's happening while it runs

With the lid off, flush the toilet and watch the tank closely. You're looking for one of two things:

• Does the flapper (the rubber piece covering the drain hole at the bottom) fully seat and seal after the flush, or does it stay slightly propped open?
• Does the water level rise until it's spilling into the overflow tube (the vertical tube in the center of the tank) instead of shutting off at the right height?

What you observe tells you which part needs attention.

Step 3: Fix a flapper that won't seal

If the flapper isn't sealing fully, check the chain connecting it to the flush lever first. Too much slack lets the chain get tangled underneath the flapper, holding it open a crack; too little slack holds it up directly. Adjust the chain so there's about a half-inch of slack when the flapper is closed.

If adjusting the chain doesn't help, the flapper itself has likely worn out, warped, or developed a mineral coating that prevents a clean seal. Replacing it is straightforward:

1. Shut off the water supply valve behind the toilet and flush to drain most of the tank.
2. Unhook the old flapper from the pegs or ring at the base of the overflow tube, and disconnect the chain.
3. Attach the new flapper (bring the old one to the store, or check your toilet model, to match sizing) and reconnect the chain with proper slack.
4. Turn the water back on and test with a few flushes.

Step 4: Fix a fill valve that won't shut off

If the flapper seals fine but water keeps rising and spilling into the overflow tube, the fill valve is the likely cause. Many fill valves have an adjustable float, either a ball on an arm or a cylindrical float around the valve itself, that tells the valve when to stop filling.

1. Locate the float adjustment (usually a screw, clip, or adjustable rod depending on your valve's design).
2. Lower the float slightly so the fill valve shuts off before water reaches the overflow tube.
3. Flush and observe again to confirm the water stops at the right level, adjusting further if needed.

If adjusting the float doesn't solve it, the fill valve itself may be worn out internally and need full replacement, which involves shutting off the water, disconnecting the supply line, and swapping in a new valve, a bit more involved but still a common weekend fix.

Step 5: Test after every change

This is worth repeating: after each adjustment, flush and watch the full cycle before moving on. It's tempting to make several changes at once, but testing one variable at a time tells you clearly what actually fixed the problem, in case it starts running again later.

What this costs you if you ignore it

A toilet running continuously at even a moderate rate can waste well over 100 gallons a day. Multiply that across a billing cycle and a running toilet you've been meaning to look at for a few weeks can already have cost you a noticeable amount by the time you finally fix it.

If you've adjusted the chain, the flapper, and the fill valve and the toilet is still running, or you're not comfortable working inside the tank, ProFlow Plumbing can track down the cause and stop the water waste before it adds up any further.