Help! My Toilet Pipe is Leaking: What Should I Do?

By: Diana Rodriguez-Zaba
Updated on: February 26, 2024

When you’re dealing with a leaking toilet pipe, how do you take care of a mess that needs cleanup and a plumbing breakdown that needs an immediate fix?

ServiceMaster by Zaba has restored water-damaged bathrooms for more than 85 years, so we know several ways to solve the problem.

Read on for insider information explaining what you should do in this situation.

Before You Get Started

  •  Turn off the stop valve at the base of the toilet’s water supply line.
  •  Flush the toilet, holding down the handle to empty the tank.
  •  Keep a bucket and dry towels within easy reach.
  •  Check your toolbox for a pipe wrench, plumber’s tape, and needle-nose pliers.

How to Fix a Leaking Toilet Pipe

how to fix a leaking toilet pipe

When a toilet’s supply line starts to leak, quick repairs help prevent serious water damage and extensive cleanup.

There are five components in a flexible toilet pipe, and each one can be the source of the leak.

Use a dry cloth to locate one of these damp areas on the pipe, and then apply the appropriate fix.

1. Leaks Directly Under the Tank

Probable Cause – Bad Coupling Nut

The coupling nut secures the flexible toilet pipe to the base of the toilet tank. Over time, it develops cracks that allow water to leak around the connection.

Fix – Gently loosen the nut with pliers, and then finish unscrewing it by hand. As it comes away from the tank, drain the open line in a bucket. Replace with a new coupling nut.

Insider Tip – Diana Rodriguez-Zaba, restoration professional, advises, “Use your fingers to secure the new coupling nut into place. Too much pressure can strip the threads or crack the plastic housing.”

2. Leaks at the Ends of Each Connection

Probable Cause – Loose Supply Line Fittings

The fitting at each end of the toilet pipe connects and secures the line between the tank and the supply valve. When one of the fittings comes loose, water drips from that end of the pipe.

Fix – Hand-tighten the loose fitting until it’s snug. Give it a final turn or two with a pipe wrench. Turn the supply valve back on, and wait until it fills the tank. Flush several times before double-checking the fitting.

Insider Tip – If the fitting still leaks, disconnect it, wrap the threads with the plumber’s tape, and secure it back into place.

Another Likely Cause – Worn Pipe Fitting Washers

A small rubber washer inside each pipe fitting ensures a watertight seal around the line connections. When it wears out, the pipe leaks under the tank or at the supply valve.

Fix – Disconnect the leaking end of the toilet pipe. Pull the washer loose from the fitting with your fingers or needle-nose pliers. Replace the part with a new washer, and reconnect the pipe.

Insider Tip – Cone washers work best in supply line fittings, but you can use a flat rubber washer as long as it fits snugly inside the fitting threads.

3. Leaks Across the Entire Length of Pipe

Probable Cause – Supply Line Failure

When a toilet pipe ages out, the rubber lining inside the flexible line begins to fail. This causes slow, continuous leaking up and down the length of the pipe. 

Fix – Disconnect the old pipe from the wall connection first, and then disconnect it from the tank. Replace with a new pipe, being careful with the coupling nut and fittings, as noted in Steps 1 and 2. 

Insider Tip – Toilet pipe supply lines aren’t universal, so take the old one to the hardware store, and let it be your guide to finding the best replacement.

4. Leaks at the Base of the Line at the Wall

Probable Cause – Faulty Shut-Off Valve

The shut-off valve connects the toilet pipe directly to your home’s plumbing system. If it becomes damaged or corroded, it leaks around the valve handle and wall plate. 

Fix – Turn off the main water supply into the house before making this repair. Disconnect the supply line at the valve. Loosen the bolts securing the valve to the wall, and then pull it off the main pipe. Attach a replacement valve, and carefully secure the line to the valve.

Insider Tip – If you have older copper pipes, this fix may require cutting the main line at the wall. It’s best to let a licensed plumber take care of the job.

How to Deal with Water Damage Caused by Toilet Leaks

A toilet pipe leak can cause multiple problems. Moisture seeps into bathroom walls, spreads through wood framing, and causes structural issues. In an upstairs bath, water can soak through the floor and ruin the ceiling below. Mold is always a concern in a water-damaged bathroom.

As soon as you fix the leak, get started with cleanup.

  • Mop up water on the floor, and wipe down wet walls.
  • Set up fans to circulate fresh air throughout the bathroom.
  • Clean surfaces with appropriate disinfecting agents.
  • Be on the lookout for signs of mold on walls or floors.

Dealing With Water Damage Due to a Toilet Pipe Leak in Chicago, IL? We Can Help!

toilet pipe leak chicago

If you’re not sure how long the toilet pipe leak went unnoticed, don’t take any chances.

Our technicians can quickly assess the damage, take care of cleanup, and restore the bathroom to its pre-leak condition. We can even help file your homeowners’ insurance water damage claim.

You want your bathroom back to normal. Call ServiceMaster by Zaba, and let us take care of everything: 773-647-1985.

Helpful Resources

Household Leak Facts – EPA

Fix a Leak Week – EPA

High-Efficiency Toilets – EPA

Is a leaking toilet pipe an emergency?

A leaking toilet pipe can be considered an emergency because it involves a water supply line. Left unattended, the leak can get worse or the line can break, spreading water damage throughout the bathroom and the house.

How do I know where my toilet is leaking from?

Use a dry cloth to feel around the flexible pipe. Start at the top, underneath the tank, and work your way down the line. When the cloth becomes damp, you’ve isolated the area of the leak.

How do you stop a water supply line from leaking?

Start by turning off the toilet’s supply valve or the main water supply to the house. Once you’ve identified the leaking part, tighten loose connections or replace the faulty component. Most DIY toilet pipe repairs are simple, but if you have any doubts, let a licensed plumber handle the job.