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What You Need to Know When the Toilet Is Leaking at the Base

A leaking toilet of any kind is a massive problem, but a leak coming from the base of your toilet packs an even bigger punch. While detecting the cause of a leaky toilet is already a challenge, a toilet leaking at the base can be simply missed. Water that seeps out of a damaged toilet will often find its way down below. So, how can we identify if the leak is coming from the lower part of the toilet rather than from other components (e.g., toilet tank, flapper, or supply line)?

A thorough inspection of your toilet and plumbing system will narrow down the real cause of your toilet leak. Only then can appropriate repairs and replacements be made. The following reasons could contribute to the pooling of water at the base of your toilet:

  • Condensation at the exterior of toilet tanks can mimic toilet leaks.
  • The bolts that anchor the toilet to the base are loose
  • The leak is coming from the water supply line.
  • The fill valve nut that fastens the water line is loose
  • Toilet was recently used and hasn’t dried up completely.
  • The bolt that anchors the base of the toilet to the floor is loose or degraded.

Water at the Base of the Toilet May Not Be a Leak

When there’s a discrepancy between the temperature of the water inside the toilet tank and the air outside, your tank may have cold sweats. The process is called condensation. Warm air coming in contact with a cold tank creates condensation. Before disassembling your toilet—looking for a loose or worn out part—check if condensation is the real culprit. The heavy amount of moisture around your toilet will drip on your bathroom floor, just like any leak.

How to Prevent Condensation:

  • As a temporary solution, install a small drip tray to keep the water off your bathroom floor.
  • Adjust your bathroom habits to prevent conditions that cause condensation: keep the door slightly open while you’re using it, or leave the fans on.
  • Insulate the toilet tank to prevent the water inside to turn cold.
  • Check if the flapper is damaged, allowing a small stream of cool water to enter the tank.
  • Replace your toilet with a new low-flow toilet that consumes less water after each flush, setting the cold tank refills at a minimum, and lowering tank sweats.
  • Plumbers recommend installing an Anti-Sweat Valve or mixing valve to warm the water before it enters the toilet tank.

Identify the Cause of the Leak

Stop using your toilet if it will take awhile before fixing it. The contaminated water seeping out of your toilet may pose a serious health risk. Dry up the water before you check for leaks. If water starts to pool from the area where the tank and base connect, your water supply line is probably compromised. Carefully tighten it with a wrench and check other parts for leaks. If the floor stays dry after mopping and drying, a mere filler or sealant could be all you need.

Flush the toilet and check if water seeps around the base of the toilet. Your toilet is securely fastened at the base with the help of T-bolts and a wax seal. When the bolts are loose or broken, it may also break the wax ring inside the toilet. Tightening the T-bolts with a wrench, while making sure your toilet is positioned correctly, is often enough to fix the problem. On its own, the wax ring can disintegrate over time, allowing dirty water to seep out of the toilet’s base. If tightening the T-bolts doesn’t work, replacing the wax ring may be necessary.

Replace a Damaged Wax Ring

The wax ring is pretty cheap, but replacing it requires unbolting the toilet from the base. This task will not be a quick or pleasant DIY project. You need an extra hand to remove the toilet or risk breaking it.

Prepare the following tools:

  • Adjustable wrench
  • Old towels and rags
  • Putty knife
  • Plastic shim (optional)
  • Caulk and caulking gun
  • Replacement wax ring
  1. Keep all your tools ready, including the replacement wax ring you just bought.
  2. Carefully unfasten the toilet and lay it down on its side on the floor. It must be drained and shut down before removal.
  3. The old wax ring must be removed or scraped from the toilet base.
  4. You may also need to replace the T-bolts, though they could be working fine even if they’re showing signs of corrosion.
  5. You can now install the new wax ring on the toilet base. If your toilet flange goes below the floor line, place an additional filler wax ring.
  6. Ask someone to assist you when reinstalling the toilet.
  7. Inspect the base of the toilet for leaks after the water is turned back on.
  8. Wait for a few days before you caulk the base because you don’t want to remove the toilet again if the problem persists or if your fix created more leaks.