How to Fix a Toilet That Leaks Between Tank and Bowl

How to Fix a Toilet Leaking Between Tank and Bowl

If water is dripping or pooling where the toilet tank meets the bowl, the seal between them has failed. This is almost always caused by a deteriorated spud washer (the large rubber gasket) or loose tank bolts. Here's how to fix it.

Why This Happens

The toilet tank sits on top of the bowl and connects through a large opening sealed by a rubber spud washer (also called a tank-to-bowl gasket). Two bolts with rubber washers hold the tank in place and help maintain the seal. Over time:

• The spud washer hardens, shrinks, or cracks
• The rubber bolt washers deteriorate
• The tank bolts loosen from vibration

Step 1: Try Tightening the Tank Bolts First

Before disassembling anything, try this quick fix:

1. Remove the tank lid
2. Locate the two tank bolts inside the tank (they go through the bottom of the tank into the bowl)
3. Hold the bolt head inside the tank with a screwdriver to keep it from spinning
4. From below the tank, tighten the nut with a wrench — alternate sides, a little at a time
5. Tighten until snug — don't overtighten or you'll crack the porcelain
6. Flush and check if the leak stops

Step 2: Replace the Spud Washer and Bolt Washers

If tightening doesn't stop the leak, the spud washer needs replacement:

What you need:

• Replacement spud washer and tank bolt kit (available at hardware stores — bring your toilet model if possible)
• Fill valve and flapper kit — good time to replace internal parts while the tank is off
• Adjustable wrench, screwdriver, sponge, bucket

Step 1: Turn off the water supply valve. Flush to empty the tank. Sponge out remaining water.

Step 2: Disconnect the supply line from the bottom of the tank.

Step 3: From below, unscrew the tank bolt nuts (hold the bolt head inside the tank with a screwdriver).

Step 4: Lift the tank straight up off the bowl and set it on a towel.

Step 5: Remove the old spud washer from the tank outlet (the large hole at the bottom of the tank). Clean the surface.

Step 6: Install the new spud washer — press it firmly into place around the tank outlet.

Step 7: Replace the rubber washers on the tank bolts.

Step 8: Lower the tank back onto the bowl, aligning the bolt holes. Hand-tighten the nuts, then snug with a wrench — alternate sides.

Step 9: Reconnect the supply line with fresh PTFE tape on the threads.

Step 10: Turn water back on, let tank fill, flush several times, and check for leaks.

Bottom Line

A toilet leaking between tank and bowl is fixed by tightening the tank bolts or replacing the spud washer. Try tightening first — it takes 5 minutes. If that doesn't work, replacing the spud washer takes about an hour and costs under $15 in parts.