How to Plumb a Toilet

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How to Plumb a Toilet

Plumbing a toilet is one of the most common home plumbing projects. Fortunately, it’s easy to do yourself if you have the right tools and supplies, but there are plenty of talented residential plumbers who can plumb a toilet for you.

First, determine the rough-in size for your toilet flange opening. This distance usually comes in at 12 inches, but some toilets require 10-inch or 14-inch rough-in sizes.

Install the Water Line

The water line that delivers fresh, clean water to your toilet tank is called a “supply line.” Over time, this line can develop leaks.

This is especially true when you’re using an older rubber water line that hasn’t been replaced in a few years. Replacing it with a metal one can help to prevent problems like cracks, breaks, and leaks.

Fortunately, installing a new supply line is fairly simple. First, you’ll want to drain all the water from your toilet.

Once you’ve drained the toilet, you can move on to replacing the water line. You’ll need a screwdriver, wrench, pliers, and some new plumbing hardware.

Start by disconnecting the water line at your shut-off valve. Then, unhook the tubing from the tank and bowl. Once both ends are loose, you can start attaching the new supply line and fittings.

Install the Stop Valve

A leaking or overflowing toilet can quickly turn into a plumbing emergency. Whether you’re doing your own repairs or calling in a plumbing professional, shutting off the water valve at the toilet’s source can ward off a major disaster.

The toilet shut-off valve is typically located at the bottom left of the toilet, on a thin pipe that leads from the toilet to the water line. It’s a simple mechanism that may be round or a lever.

It’s easy to install a new stop valve yourself and save a few bucks at the same time. All you need is a few basic tools.

If the old toilet valve is a compression valve, remove the nut and compression rings using a pair of pliers while holding the pipe. You can also cut off the compression ring with a tube cutter, as close to the old nut as possible.

Install the Toilet Flange

The toilet flange is a crucial component of any toilet. It not only helps to connect the toilet with the water line but also holds it in place, making it stable and secure.

If your toilet flange is in poor condition or damaged, it might be time to replace it. A new flange will be more durable and fit your toilet better.

Start by removing the old toilet flange. If it’s plastic, you can glue on a new one and fix it at the right elevation for your floor (if not, remove it).

Next, bore holes around the flange ring equidistant from each of four points directly into the concrete subfloor, so you can bolt it in. Using Tapcon anchors or similar masonry/concrete screws, fasten the flange to the concrete.

Once the flange is in place, install a replacement wax ring and center it over the flange before lowering the toilet bowl. This prevents the flange from leaking when you flush.

Install the Toilet Bowl

Once you have the toilet flange and water supply line installed, it’s time to install the bowl. Be sure to check the flange and bolts for any leaks before you begin to work.

Use a carpenter’s level to make sure the bowl is level as you lower it into place. Once the bowl is on the flange, align the holes in the base with the flange bolts and gently but firmly press it down to set the wax ring seal.

After the bowl is positioned, slip stainless steel washers into any gaps to ensure that it sits evenly. Next, tighten the nuts to hold it in place. Alternate from nut to nut, and be careful not to over-tighten or you’ll crack the porcelain bowl.

After the tank is on, replace the washers and nuts that are usually included with the toilet and tighten them in the same way as the floor bolts. Tighten them gradually, alternating from one side to the other to apply even pressure.

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Casey Loeber

Casey Loeber is the founder of His mission is to share the best information online about plumbing jobs and help plumbers lead fulfilling careers.

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